D-Lib Magazine
September 2001

Volume 7 Number 9

ISSN 1082-9873

Networked Digital Library of Theses and Dissertations

Bridging the Gaps for Global Access - Part 1: Mission and Progress



Hussein Suleman, Anthony Atkins, Marcos A. Gonçalves, Robert K. France, Edward A. Fox
(hussein, anthony.atkins, mgoncalv, france, fox)
Virginia Tech

Vinod Chachra, Murray Crowder
(chachra, crowderm)

Jeff Young

Red Line



The Networked Digital Library of Theses and Dissertations (NDLTD) is a collaborative effort of universities around the world to promote creating, archiving, distributing and accessing Electronic Theses and Dissertations (ETDs). Since its inception in 1996, over a hundred universities have joined the initiative, underscoring the importance institutions place on training their graduates in the emerging forms of digital publishing and information access. The outreach and training mission of NDLTD is an ongoing project so in this article we report on the current status of membership and support activities. Recent research has focused on creating a union database that will provide a means to search and retrieve ETDs from the combined collections of NDLTD member institutions. The Virtua system developed by VTLS will serve as the heart of this union database. In order to bridge the gap between the existing distributed institutional archives and a unified collection of ETDs, we have developed a metadata standard especially suited to ETDs - this is then used by partner sites to export their freely-available metadata using the Metadata Harvesting Protocol of the Open Archives Initiative. We also link name authority information into the metadata records to support unique identification of authors and others associated with the works. Additional research efforts include advanced search mechanisms, semantic interoperability, the design and development of multi- and cross-lingual search systems, and software modules that support the development of higher-level services to aid researchers in seeking relevant ETDs.


The Networked Digital Library of Theses and Dissertations (NDLTD, see has emerged as a result of the efforts of thousands of students, faculty, and staff at hundreds of universities around the world, as well as the assistance of interested parties at scores of companies, government agencies, and other organizations. This federation has multiple objectives, including:

  • to improve graduate education by allowing students to produce electronic documents, use digital libraries, and understand issues in publishing;
  • to increase the availability of student research for scholars and to preserve it electronically;
  • to lower the cost of submitting and handling theses and dissertations;
  • to empower students to convey a richer message through the use of multimedia and hypermedia technologies;
  • to empower universities to unlock their information resources; and
  • to advance digital library technology.

Work toward those objectives has proceeded since November 1987, the date of the first meeting devoted to exploring how advanced electronic publishing technologies could be applied to the preparation of electronic theses and dissertations (ETDs). Early efforts are summarized in two D-Lib articles in 1996 and 1997 [Fox et al, 1996; Fox et al., 1997]. A third article summarizes the first attempts to support, through federated search, access to the collection (see also of ETDs that is emerging in distributed fashion [Powell & Fox, 1998].

NDLTD activities are coordinated by an international steering committee that meets each spring and fall. Its members include those who lead the diverse regional and national efforts that promote efforts regarding ETDs. Committees help with strategic planning, standards (see, training, and meetings. A good deal of effort by steering committee members has gone into fund-raising, so that single and groups of institutions could implement ETD initiatives. There have been national projects in the USA [Kipp, et al., 1999], South Africa, Germany, Australia, and other countries. Supporting research work has been funded by NSF (in projects IIS-9986089 [Fox, 2000], IIS-0086227 [Fox, et al. 2000], IIS-0080748 [Fox, et al., 2001]), as well as DFG (in Germany) and CONACyT (in Mexico).

At the grass roots level, one line of support for NDLTD emerged from efforts at Virginia Tech, which has developed training materials and workflow management software that have been adapted by diverse groups. Many other projects and programs interested in ETDs have arisen around the world, some independently, but all are welcome to collaborate through the growing federation that is NDLTD. This is important since open sharing of methods helps others know how to address problems as well as ongoing changes in technology. Already there have been four international symposia on ETDs, with approximately 200 attendees at each of the last two. The next two will be held May 30 - June 1, 2002 at Brigham Young University in Provo, Utah, and late spring, 2003, in Berlin. The NDLTD steering committee has its spring meetings in conjunction with the ETD conferences.

These efforts should have a strong positive effect on expanding awareness at universities around the globe. One important agent promoting learning in this arena is the UNESCO International Guide for the Creation of ETDs (see <>). To be released late in 2001 in a number of different languages, this book / web site should help students, faculty, and administrators participate in NDLTD. This should extend the considerable progress already made, as is discussed in the next section.

NDLTD Progress

NDLTD has experienced constant progress since its formation. We have registered growth in all major facets, including membership (with an increasing international participation), collection size, access, multimedia use, and worldwide availability.


Table 1 shows NDLTD membership as of August 2001. In less than two and a half years, NDLTD has more than doubled the number of registered members (from 59 members in May 1999). There are currently 120 members; 52 U.S. universities, 52 non-U.S. universities, and 16 institutions, regional centers and organizations (such as UNESCO). These various partners represent 23 countries: Australia, Brazil, Canada, China, Colombia, Germany, Greece, Hong Kong, India, Italy, Mexico, Netherlands, Norway, Russia, Singapore, South Africa, South Korea, Spain, Sudan, Sweden, Taiwan, the USA, and the United Kingdom. These numbers also emphasize the growth of global interest in NDLTD as international participation grew from less than one third in 1998 to half of the total membership in 2001. Also, by early 2002, at least 11 of the registered NDLTD members will have started requiring mandatory submission of electronic theses and dissertations. (In the table below, those are marked with an asterisk.)


USA Universities (524)

International Universities (512)

Institutions (156)

Air University (Alabama)

Alicante University

Baylor University

Brigham Young University

California Institute of Technology

Clemson University

College of William and Mary

Concordia University (Illinois)

East Carolina University

East Tennessee State University*

Florida Institute of Technology

Florida International University

George Washington University

Louisiana State University*

Marshal University

Massachusetts Institute of Technology

Miami University of Ohio

Michigan Tech

Mississippi State University

Montana State University

Naval Postgraduate School

New Jersey Institute of Technology

New Mexico Tech

North Carolina State University*

North Western University

Pennsylvania State University

Regis University

Rochester Institute of Technology

Texas A&M University

University of Colorado

University of Florida

University of Georgia

University of Hawaii at Manoa

University of Iowa

University of Kentucky

University of Maine*

University of North Texas*

University of Oklahoma

University of Pittsburgh

University of Rochester

University of South Florida

University of Tennessee, Knoxville

University of Tennessee, Memphis

University of Texas at Austin*

University of Utrecht

University of Virginia

University of West Florida

University of Wisconsin, Madison

Vanderbilt University

Virginia Commonwealth University

Virginia Tech*

West Virginia University*

Western Michigan University

Worcester Polytechnic Institute

Alicante University (Spain)

Australian National University (Australia)

Biblioteca de Catalunya (Spain)

Chinese University of Hong Kong (Hong Kong)

Chungnam National U., Dept of CS (S. Korea)

City University, London (UK)

Curtin University of Technology (Australia)

Darmstadt University of Technology (Germany)

Freie Universitat Berlin (Germany)

Gerhard Mercator Universitat Duisburg (Germany)

Griffith University (Australia)

Gyeongsang National University, Chinju (Korea)

Humboldt-Universität zu Berlin (Germany)

Indian Institute of Technology, Bombay (India)

Lund University (Sweden)

McGill University (Canada)

National Sun Yat-Sen University (Taiwan)

Nanyang Technological University (Singapore)

National University of Singapore (Singapore)

Rand Afrikaans University (South Africa)

Rhodes University (South Africa)*

Shanghai Jiao Tong University (China)

St. Petersburg State Technical U. (Russia)

State University of Campinas (Brazil)

Sudanese National Electronic Library (Sudan)

Universidad de las Amèricas Puebla (Mèxico)

Universitat Autonoma de Barcelona (Spain)*

Universitat d'Alacant (Spain)

Universitat de Barcelona (Spain)

Universitat de Girona (Spain)

Universitat de Lleida (Spain)

Universitat Oberta de Catalunya (Spain)

Universitat Politecnica de Catalunya (Spain)

Universitat Politecnica de Valencia (Spain)

Universitat Pompeu Fabra (Spain)

Universitat Rovira i Virgili (Spain)

Universitè Laval (Quèbec, Canada)

University of Bergen (Norway)

University of Antioquia (Medellin, Colombia)

University of British Columbia (Canada)

University of Guelph (Ontario, Canada)

University of Hong Kong*

University of Melbourne (Australia)

University of Mysore (India)

University of New South Wales (Australia)

University of Pisa (Italy)

University of Queensland (Australia)

University of Sao Paulo (Brazil)

University of Sydney (Australia)

University of Utrecht (Netherlands)

University of Waterloo (Canada)

Uppsala University (Sweden)

Wilfrid Laurier University (Canada)


Coalition for Networked Information

Committee on Institutional Cooperation

Consorci de Biblioteques Univers. Catalunya

Dissertationene Online


Ibero-American Sci. & Tech. Ed. Cons. (ISTEC)

National Documentation Centre (NDC, Greece)

National Library of Portugal



Organization of American States (OAS)


Sudanese National Electronic Library (Sudan)

Solinet UNESCO


Table 1. NDLTD Membership


Collection Size

The number of ETDs across the NDLTD universities/institutions has grown at an even faster pace. From a few dozen at Virginia Tech in 1996, to 4,328 ETDs at 21 institutions in March 2000, we accounted for a total of 7,268 ETDs at 25 member institutions in July 2001. Table 2 shows a breakdown of the current numbers of ETDs as of July 2001 organized by member institution. This data is largely the result of an on-line survey conducted by Gail McMillan and represents only those institutions that responded to the survey.



ETD Collection size

ADT: Australian Digital Thesis Program (Australia)


University of Bergen (Norway)


California Institute of Technology


Consorci de Biblioteques Universitaries de Catalunya (Spain)


East Tennessee State University


Humboldt-University (Germany)


Louisiana State University


Mississippi State University




North Carolina State University


Pennsylvania State University


Pontifical Catholic University (PUC) (Brazil)


Gerhard Mercator Universitat Duisburg (Germany)


Universitat Politecnica de Valencia (Spain)


University of Florida


University of Georgia


University of Iowa


University of Kentucky


University of Maine


University of North Texas


University of South Florida


University of Tennessee


University of Tennessee, Knoxville


Uppsala University (Sweden)


Virginia Tech


West Virginia University


Worcester Polytechnic Institute





Table 2. NDLTD collection size


These statistics do not take into account scanned theses and dissertations, which make up a substantial portion of the total NDLTD collection. There are 26 scanned documents at the New Jersey Institute of Technology, 150 at the University of South Florida, 5,581 at MIT, and 12,000 at the National Documentation Center in Greece. These result in a total of 17,763 scanned theses and dissertations at these institutions, and quite conceivably thousands of unreported ones at other institutions.

Access Statistics

To demonstrate the potential of NDLTD for global access and sharing of the knowledge produced by universities worldwide, we have periodically analyzed the access logs of the Virginia Tech ETD (VT-ETD) collections. The results for the period 1997-2000 are shown below in Table 3.








Requests for PDF files
(mostly full ETDs)






Requests for HTML files
(mostly tables of contents and abstracts)






Requests for multimedia






Distinct files requested






Distinct hosts served






Average data transferred daily

156,089 KMbB

219,132 KMbB


382 MbMB


Data transferred

55,637 MbGB

78,107 MbGB


137 GbGB



Table 3. Access Log Statistics from the VT-ETD collection


We can see that the number of accesses tends to increase each year. As the collection grows and gains popularity, the number of accesses will most likely continue to increase.

More specifically, Table 4 indicates that each of the seven countries with the most accesses has an increasing number of accesses each year (with the exception of Germany in the 97/98 - 98/99 period). The United Kingdom, and surprisingly Malaysia, dominated accesses from outside the US. The other accessing countries are all European, a fact that is probably related to advances in network infrastructure in those countries.


International Domain


1997/98 rank


1998/99 rank



1999/00 rank


United Kingdom
































































Table 4. Access by Non-US Sites


Multimedia Use in ETDs

One of the main objectives of NDLTD is to promote student creativity through the use of diverse types of multimedia content in ETDs, while making students comfortable with the use of this technology to exploit richer modes of self-expression.

Table 5 indicates how much of this objective has been achieved in the VT-ETD collection, with a breakdown of the 8,056 multimedia files contained in a selection of 2,180 available ETDs. This illustrates both that authors are beginning to shift towards non-textual media and that some are moving away from the early single-file paradigm of digitization.

File type



Still image BMP, DXF, GIF, JPG, TIFF








Other Macromedia, SGML, XML


Table 5. Multimedia use in VT-ETD collection


Worldwide Release

In terms of copyright, a significant issue is whether to allow the electronic document to be viewed worldwide, on campus only, or not at all. The “mixed” case, which is a unique capability of electronic documents, occurs when some portions (e.g., particular chapters or multimedia files) have restricted access while others are more widely available. The majority of Virginia Tech students allow their documents to be viewable worldwide (see Figure 1) - but some initially choose not to grant worldwide access in order to protect their publication rights. To address this concern, there are ongoing discussions with publishers to help them understand the goals and benefits of NDLTD [NDLTD, 1999]. We are pleased to see a change in attitude by some publishers over the course of the project. The American Chemical Society developed a policy more favorable to NDLTD as a result of lengthy discussions and the American Physics Society has been receptive to issues concerning the Open Archives Initiative and NDLTD.


Graph  showing student and committee preferences for ETD availability

Figure 1. Student and committee choice for ETD availability from Virginia Tech
(2668 ETDs as of July 17, 2000).


Standards Activity

In order to support many of the current and future research and service-related activities, work has begun to define standards that will enable more consistent exchange of information in an interoperable environment. Among the first of these projects is ETDMS - the Electronic Thesis and Dissertation Metadata Standard - and a related project for name authority control.

Electronic Thesis and Dissertation Metadata Standard (ETDMS)

ETDMS was developed in conjunction with the NDLTD, and has been refined over the course of the last year. The initial goal was to develop a single standard XML DTD for encoding the full text of an ETD. Among other things, an ETD encoded in XML could include rich metadata about the author and work that could easily be extracted for use in union databases and the like. During initial discussions it became clear that the methods used by different institutions to prepare and deal with theses and dissertations would make it all but impossible to agree on a single DTD for encoding the full text of an ETD. Many institutions were unwilling or unprepared to use XML to encode ETDs at all.

Thus, instead of an XML DTD for encoding the full text of an ETD, ETDMS emerged as a flexible set of guidelines for encoding and sharing very basic metadata regarding ETDs among institutions. Separate work continues in parallel on a suite of DTDs, building on a common framework, for full ETDs.

ETDMS is based on the Dublin Core Element Set [DCMI, 1999], but includes an additional element specific to metadata regarding theses and dissertations. Despite its name, ETDMS is designed to deal with metadata associated with both paper and electronic theses and dissertations. It also is designed to handle metadata in many languages, including metadata regarding a single work that has been recorded in different languages. The ETDMS standard [Atkins, et al., 2001] provides detailed guidelines on mapping information about an ETD to metadata elements.

ETDMS already is supported as an output format for the Open Archives interface to the Virginia Tech ETD collection. ETDMS will be accepted as an input format for the union catalog currently being developed in conjunction with VTLS [VTLS, 2001]. NDLTD strongly encourages use of ETDMS.

Authority Linking

Each reference to an individual or institution in an ETDMS field should contain a string representing the name of the individual or institution as it appears in the work. In addition, these references also may contain a URI that points to an authoritative record for that individual or institution. Associating authority control with NDLTD seems particularly appropriate since universities know a great deal about those to whom they award degrees and since a thesis or dissertation often is the first significant publication of a student.

The “NDLTD: Authority Linking Proposal” [Young, 2001] identifies several goals for a Linked Authority File (LAF) system to support this requirement:

  • LAF records should be freely created and shared among participants. While a central authority database is an option, the LAF design expects the database to be distributed to share cost. Individual participants or groups should be able to host a copy of the LAF database and share changes they make to local copies of LAF records with other hosts using the Open Archives Initiative (OAI) protocol [Lagoze and Van de Sompel, 2001]. The mechanism for keeping records in sync is described in the proposal.
  • The URIs should be meaningful and useful to anyone outside NDLTD’s domain. A benefit of using the OAI protocol is that individual LAF records will be accessible via an OAI GetRecord request (discussed in the second part of this article).
  • The URIs should be persistent and current. This raises a number of challenges, such as duplicate resolution. By using PURLs [OCLC, 2001] in ETDMS records, the underlying OAI GetRecord URLs can be rearranged without affecting the ETDMS records that rely on them.
  • The model should be scalable and applicable beyond NDLTD. The LAF model was designed to work entirely with open standards and open-source software.

The LAF design has other advantages over alternatives such as the Library of Congress Name Authority Database [Library of Congress, 2001]. Only the level of participation among decentralized participants limits the coverage of the collection. Because the records are based on XML, the content of LAF records can be as broad or narrow as needed. Finally, because they are distributed using the OAI protocol, multiple metadata formats can be supported.

Future of NDLTD

The statistics presented illustrate that the production and archiving of electronic theses and dissertations is fast becoming an accepted part of the normal operation of universities in the new electronic age. NDLTD is dedicated to supporting this trend with tools, standards, and services that empower individual institutions to set up and maintain their own collections of ETDs. At the same time NDLTD promotes the use of these ETDs through institutional websites as well as portal-type websites that aggregate the individual sites and create seamless views of the NDLTD collection.

Ongoing research and service-provision projects are addressing the problems of how to merge together the currently distributed and somewhat isolated collections hosted at each member institution. The second part of this article discusses some of these projects in detail, including development of the Union Catalog Portal based on VTLS’s Virtua system and the myriad of research efforts investigating how to provide better services to researchers with specific information-seeking needs and behaviors.


Atkins, Anthony, Edward A. Fox, Robert France and Hussein Suleman (editors). 2001. ETD-ms: an Interoperability Metadata Standard for Electronic Theses and Dissertations -- version 1.00. Available from <>.

DCMI. 1999. Dublin Core Metadata Element Set, Version 1.1: Reference Description. Available from <>.

Fox, Edward A. 2000. Core Research for the Networked University Digital Library (NUDL), NSF IIS-9986089 (SGER), 5/15/2000 - 3/1/2002. Project director, E. Fox.

Fox, Edward A., John L. Eaton, Gail McMillan, Neill A. Kipp, Laura Weiss, Emilio Arce, and Scott Guyer. 1996. National Digital Library of Theses and Dissertations: A Scalable and Sustainable Approach to Unlock University Resources, D-Lib Magazine, September 1996. Available at <>.

Fox, Edward A., Brian DeVane, John L. Eaton, Neill A. Kipp, Paul Mather, Tim McGonigle, Gail McMillan, and William Schweiker. 1997. Networked Digital Library of Theses and Dissertations: An International Effort Unlocking University Resources, D-Lib Magazine, September 1997. Available at <>.

Fox, Edward A., Royca Zia, and Eberhard Hilf. 2000. Open Archives: Distributed services for physicists and graduate students (OAD), NSF IIS-0086227, 9/1/2000-8/31/2003. Project director, E. Fox (w. Royce Zia, Physics, VT, and E. Hilf, U. Oldenburg, PI on matching German DFG project).

Fox, Edward A., J. Alfredo Sánchez, and David Garza-Salazar. 2001. High Performance Interoperable Digital Libraries in the Open Archives Initiative, NSF IIS-0080748, 3/1/2001-2/28/2003. Project director, E. Fox (with co-PIs J.Alfredo Sánchez, Universidad de las Américas-Puebla --- UDLA, and David Garza-Salazar, Monterrey Technology Institute --- ITESM, both funded by CONACyT in Mexico).

Kipp, Neill, Edward A. Fox, Gail McMillan, and John L. Eaton. 1999. FIPSE Final Report, 11/30/99. Available from <> (PDF version) and <> (MS-Word version).

Lagoze, Carl and Herbert Van de Sompel. 2001. The Open Archives Initiative Protocol for Metadata Harvesting. Open Archives Initiative. January 2001. Available from <>.

Library of Congress. 2001. Program for Cooperative Cataloguing Name Authority Component Home Page. Available from <>.

NDLTD. 1999. Publishers and the NDLTD. NDLTD, July 1999. Available from <>.

OCLC. 2001. Persistent URL Home Page. Dublin, OH: OCLC Online Computer Library Center. Available from <>.

Powell, James and Edward A. Fox. 1998. Multilingual Federated Searching Across Heterogeneous Collections. D-Lib Magazine, September 1998. Available at <>.

VTLS. 2001. Virtua ILS. Available from <>.

Young, Jeffrey A. 2001. NDLTD: Authority Linking Proposal. Dublin, OH: OCLC Online Computer Library Center. Available from <>.

Copyright 2001 Hussein Suleman, Anthony Atkins, Marcos A. Gonçalves, Robert K. France, Edward A. Fox, Vinod Chachra, Murray Crowder, and Jeff Young

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DOI: 10.1045/september2001-suleman-pt1