# Presentation: 686937

## Reference/Citation Linking and CrossRef

June 21, 2000

Ed Pentz
Executive Director
CrossRef

**Reference/Citation Linking and CrossRef**
**June 21, 2000**
**Ed Pentz**
**Executive Director**
**CrossRef**

**Notes:**
Good Morning

I’m very happy to have the chance to address you today and give you an update on CrossRef.   I’m honored and a little nervous to be following Dr Kahn but he has provided an excellent introduction to my talk on CrossRef – CrossRef is a practical implementation of many of the ideas he talked about.   I’m here representing a new and unusual organization in the world of scholarly journal publishing.  As you’ve heard, since February of this year I have been Executive Director of CrossRef – CrossRef is an innovative web-based service to enable reference links between online journals. 

## “Although I’ve never met anyone at a record company 

- who ‘believed in the Internet,’ they’re all trying to cover
- their asses by securing everyone’s digital rights”
*Courtney Love (Salon.com)*

- Publishers may or may not believe in the Internet,
- but they are all covering themselves by linking,
- especially to full text articles

**Notes:**
SLIDE – The Internet is a disruptive technology – it is radically changing all areas of society and it has been having a huge impact on scholarly journal publishing since the advent of the WWW and web browsers six or so years ago. A quotation from Courtney Love  in the online magazine salon.com sums up the effect the WWW is having on the music industry.  Paraphrasing this quote, and using more suitable language, sums up publishers’ attitudes towards reference linking.  
The Internet and WWW are disruptive technologies, but I think that sometimes the claims that the Internet will “change the world” can be overstated.  The Internet can change things radically but it’s also important to remember that the Internet can improve and enhance already existing processes and the Internet itself won’t necessarily convince people to change their ways.  An example of this is Paul Ginsparg’s Physics Preprint Server run at Los Alamos - it has be very successful but one of the reasons it has been successful is that sending out preprints had been part of the physics, particularly High Energy Physics, culture well before the electronic preprint server started.  The preprint server enhances and makes an existing process more efficient but pre-print servers have not been widely adopted in other disciplines.

## Reference, n.
5. a. A direction to a book, passage, etc., where certain information may be found; an indication of the author, work, page, etc., to be looked at or consulted. 
BRINSLEY Lud. Lit. xiii. (1627) 188 If they had but only bookes of References, it would be exceeding profitable. 
			Oxford English Dictionary 

**5. a.** A direction to a book, passage, etc., where certain information may be found; an indication of the author, work, page, etc., to be looked at or consulted.
- BRINSLEY *Lud. Lit.* xiii. (1627) 188 If they had but only bookes of References, it would be exceeding profitable.
- 			*Oxford English Dictionary*

**Notes:**
So, this is a long introduction to reference linking. As background to CrossRef I think it’s useful to take a step back and look at the importance of reference linking.  A definition of the word “reference” from the Oxford English Dictionary is a useful starting point.  Reference linking is a key part of scientific communication.  A quote from the OED illustrates this very well - the quote is from 1612, decades before the first journals were published.  It says - “if they had but only books....”  So the value of references has been seen for a long time.

## Reference Linking

- Gives end users access to logically related articles in one or two clicks
- Allows body of primary literature to be seen as group of logically associated articles
- Researchers want and expect everything to link

- Links =
- Added Value

- No Links =
- Decreased Value

**Notes:**
Through reference links in online journals, users can access logically related articles in one or two clicks.  Reference links in online journals enhance a process that has been going on for hundreds of years.  But the ease of use is a major change from the print world where following a chain of references is very difficult.  Being able to easily access cited articles means that a wide body of scientific literature can be viewed as a related group. 
Therefore, reference links are seen as very valuable and researchers want and expect everything to link.  This is especially true now that most scholarly journals are online and are moving beyond just replicating what’s in print and starting to take advantage of the electronic environment.  So reference links equals added value.  However, things have gone one step beyond this and not having links actually decreases the value of a journal.

## Why CrossRef?

- Market pressure to link
- Current Linking
- Closed Links - only within journal systems
- Links between large secondaries and large primaries - small publishers left out, primaries not linking to each other
- Linking Agreements
- Bilateral agreements
- Define terms of linking/“no surprises”

**Notes:**
So, why is CrossRef necessary.  Well there is pressure from the market, scientists and librarians, to link.  Of course, linking is already happening, if publishers want to link they can just link.  There are already many reference links and links to full text in place without CrossRef.  HighWire Press, CatchWord, ISI’s Web of Science and others all have linked for some time now.  However there are limitations to the current linking.  First of all, for the most part linking has been within one journal system – closed links really.  Or large secondary databases are linking to large publishers and vice versa. What is missing is large-scale, broad-based linking between primary publishers and links to smaller publishers, mainly society publishers.  One reason linking has been limited is that organizations have been signing bilateral linking agreements – this is necessary to specify the terms of linking and make sure that there are “no surprises”.  The legal issues surrounding linking are not clear, there have been a couple of cases decided about linking but publishers have been signing linking agreements. Having worked on linking agreements at Academic Press I can attest to the fact that they take up a lot of time.

## Why CrossRef?

- 2-party agreements not scalable
- too many publishers (primary and secondary)
- ISI has linking agreements with 15 publishers
- Result - Publishers cooperating!
- CrossRef makes broad-based linking manageable

**Notes:**
Publishers signing bilateral agreements is not scalable across all of scholarly publishing.  ISI links from Web of Science and they have signed agreement with 15 publishers - considering the number of journals in the ISI system that doesn’t seem like very much. Confronting this problem lead to unprecedented cooperation between publishers and the formation of CrossRef in a very short space of time.  I heard people say getting publishers to cooperate is like herding cats – well ... many of the cats have been herded – at least for the time being.

## Reference Linking Infrastructure

- How is a link to an article created from a standard citation?
- Algorithmic Link - bibliographic metadata
- Article Identifier w/ resolution system
- To create algorithmic links -
- a publisher needs to know the linking scheme of every cited publisher and when it changes
- publisher needs to know if the article is online - massive data collection problem

**Notes:**
The basic question regarding reference linking is - how is a link to an article created from a standard citation.  This can be done in two ways - with use bibliographic metadata to construct a URL - these are algorithmic links and the main way links are created at the moment.  The other way is by assigning persistent identifiers to an article and using a resolution system to get from the identifier to a URL.
The problem with algorithmic links is that to create a link, a publisher needs to identify which publisher published the cited article (not easy when all there is in many citations is a journal abbreviation) and then know what linking scheme they use.  If the linking scheme changes that all links need to be updated.  The other crucial thing is a publisher needs to know if an article is online - so a publisher needs to know the online availability of all the cited articles - a major data collection issue.

## Article Identifier

- Digital Object Identifier (DOI)
- Handle System - CNRI
- unique, persistent, soon to be NISO standard
- DOI System routes a DOI to a URL registered by publisher
- With a DOI -
- linker doesn’t need to know publishers’ linking systems or if they change
- if a publisher changes their URLs, they only need to be updated in one place
- article is guaranteed to be online (only articles online get DOIs)

## DOI

- DOI Problem
- how do you know what the DOI is for an article?
- CrossRef provides a database of DOIs and a DOI Lookup service (telephone book and directory assistance)

## The CrossRef Process

- Publishers deposit article metadata (including DOIs) in CrossRef database
- Publishers submit references from articles to CrossRef to lookup DOIs
- Publishers use DOIs to create reference links in their online journals
- User clicks on reference links and goes to other Publisher’s site

## WORKFLOW FOR REFERENCE LINKING

- 3. Journal production systems export articles with DOIs

- 2. DOI Lookup: a Journal production system requests a DOI based on citation metadata

-  1. Journal production systems export metadata to MDDB as new articles are published

- 4. Users may request
- and retrieve articles via DOI resolution system

- CrossRef MDDB

- Publisher Online Journal System

- Publisher Production System

## CrossRef 

- Not-for-profit, membership organization
- Members: publishers of original scholarly material
- Users: members and any organization creating links to full text articles
- Purpose 1: Enable links from primary article references to the cited articles at other publishers’ sites
- Purpose 2: Enable links to full text articles from secondary services

## Organization

- Publishers International Linking Association (PILA) - incorporated February 2000
- Board of Directors
- AAAS (Science),Academic Press (Harcourt), AIP, ACM, Blackwell Science, Elsevier Science, IEEE, Kluwer, Nature, OUP, Springer, Wiley

## Business Rules/Governance

- CrossRef Membership
**Provide full bibliographic citation for incoming DOI links**
- many publishers will give free abstracts
- information on acquiring article (pay online, document delivery, subscription)
- Access to abstracts and full text controlled by publishers
- CrossRef guarantees links

## Current Status

- Reference links are live!!
- 1100 journals have links (Elsevier, Academic Press, Wiley, Springer, Blackwell Science)
- Metadata deposited for 1.3 Million articles from 2700 journals
- 3 million articles by end of year
- 0.5-1 million new articles per year

## AAAS (Science) 
Academic Press (Harcourt)
ALPSP 
American Chemical Society
American Geophysical Union
American Institute of Physics 
American Mathematical Society 
American Physical Society
American Psychological Assoc
ACM 
Annual Reviews
Blackwell Science/Blackwell Publishers 
British Medical Journal
CAB International
Cambridge University Press 
Elsevier Science

- Academic Press (Harcourt)
- ALPSP
- American Chemical Society
- American Geophysical Union
- American Institute of Physics
- American Mathematical Society
- American Physical Society
- American Psychological Assoc
- ACM
- Annual Reviews
- Blackwell Science/Blackwell Publishers
- British Medical Journal
- CAB International
- Cambridge University Press
- Elsevier Science

- IEE
- IEEE
- Institute of Physics
- Kluwer Academic
- Marcel Dekker
- Mary Ann Liebert
- Nature
- Oxford University Press
- Portland Press
- The Royal Society
- Royal Society of Chemistry
- Springer
- Taylor & Francis
- Thieme Verlag
- University of Chicago Press
- John Wiley & Sons
- World Scientific

## CrossRef Fees

- Member Fee
- Annual Administrative Fee
- Deposit Fee
- Lookup Fee
- Principles
- cost recovery
- flexibility
- no charges to end users to follow links

## Fees

**Primary Publisher Annual Member Fee****	**
- 1 title, max 500 articles per year		   *$200*
- 2-5 titles, max 2,500 articles per yr		   *$500*
- 6-20 titles, max 10,000 articles per yr	        	   *$750*
- 21-100 titles, max 50,000 articles per yr*	**$1,000*
- >100 titles or >50,000 articles per yr		*$2,000*
**Non-Member Annual Administrative Fee**
- Secondary, database <100,000 records/yr	*$2,000*
- Secondary, database >100,000 records/yr	*$5,000*
- Agents	* **	**	**	**	**	**$5,000*
- Non-resellers (e.g., libraries)			   *$300*

## Fees

**Deposit Fee for Primary Material**
- Current Year -- full text			$0.60
- Back File (deposit after 10/1/2000)		$0.10
- Back File	(prior to 10/1/2000)		$0.05

## Fees

**Member Retrieval Fee **(for successful match)
- Per DOI matched				$0.05
**Non-Member Retrieval Fee **(for successful match)
- Per DOI Matched 				$0.10

## Future Developments

- Multiple Resolution
- one DOI = one URL is starting point
- multiple locations and multiple files
- Appropriate Copy Issue
- Collaboration
- DLF/IDF/CNRI/CrossRef, libraries, publishers
- Interoperability
- Metadata is “system neutral”

## Contact	Details

- www.crossref.org
- Ed Pentz - epentz@crossref.org

## Metadata Deposit

- Publishers submit article metadata
- Journal Title, ISSN/Coden,Volume, Issue, First Page, First Author, Year - mandatory
- Article Title is optional
- XML-based DTD (DOI-X)
- Formal grammar
- Supplementary “data rules”
- Journal articles today
- conference proceedings and more to follow

## DOI Lookup

- Publishers submit references to Reference Resolver (RR)
- References tagged in SGML/XML
- Minimum Data
- Abbreviated title, volume, first page - possibly first author and year
- Send Batches of References
- RR - intelligent “link agent”