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Library Resource Identifiers -- Call Number, Barcode, ISBN, ISSN, DOI and Persistent Link: Home

Call Number


A call number on the book spine tells the user where the book is specifically and physically located on the shelf. Functioning like a book's address in the library, a book call number is a combination of letters and numerals labeled at the bottom of the book spine. Each book's call number is unique.

To find one particular book on the shelf, you have to know its call number first, which you obtain by searching either the classic catalog or OneSearch. The first letter(s) represent(s) the subject associated with the book. For instance, H is for social science and RT is for nursing. Once you find the book you are looking for, you will notice that the neighboring books bear the same or similar subjects. Letters are read in alphabetical order and numbers in numerical order. (Hint: Remember that everything after the decimal is read as a decimal.) The whole call number system is called the Library of Congress (LC) Classification system. Sometimes books in different collections at York have different prefixes on their spine labels, which tell books' locations, too. For example, REF for reference collection, RESE for materials put in the Circulation and Reserve, and CMC for the Curriculum Materials Center (children and juvenile literature collection). Books in the general Stacks collection don't bear a prefix. This picture below shows what call numbers look like on the shelf in the general collection.

Examples of Call Numbers


Each book has a unique barcode, which is usually affixed to the last page prior to the back cover in our library's books, or sometimes to an interior page to avoid covering significant text. As the system inventory number for each book, barcodes can be read electronically. When you take the book to the Circulation Desk, its barcode will be scanned into the computer system, you will be told how long you can keep the book out and when you should return it. Due to system migration in the past, our library has a substantial number of books that don't have barcodes. If you come across books without barcodes, please kindly take them to the Circulation Desk, and they will be passed on to cataloging professionals so that they can get barcodes and be checked out.

Examples of Barcodes


International Standard Book Number (ISBN)

Generally speaking, ISBNs are nationally or internationally standardized numbers that publishers obtained for monographic publications from the affiliated ISBN agency. The ISBN, assigned on or after 1 January 2007, has 13 digits and 10 digits if assigned before 2007.

"Each ISBN is unique to a title, edition of a book, or monographic publication -- braille, microform, and electronic publications, as well as audiobooks, educational/instructional videos/DVDs and software -- published or produced by a specific publisher or producer." That means a paperback, a hardcover, and an ebook of the same title will have a different ISBN. ISBN is an effective identifier to help you locate a particular book in the library system.  

An Example of ISBN

International Standard Serial Number (ISSN)

ISSNs are eight-digit, unique, standardized numbers assigned to serial publications, such as magazines and journals, for the purpose of registering, ordering, and cataloging. An ISSN is an effective access point that helps one locate a specific serial in the library system, which can be very helpful especially since sometimes more than more journal has the same (or a similar) title. An official ISSN is usually formatted with a hyphen between the first four digits and the last four digits. When a serial is published in various media, a linking ISSN or ISSN-L will be assigned to group them together.

An Example of ISSN

Digital Object Identifier (DOI)

A Digital Object Identifier (DOI) is a unique code mainly assigned to each article in academic journals. It can also be used for book chapters and other publications when it is considered necessary by publishers, too. The format of DOI is quite different from that of ISBN and ISSN, and it usually includes numerals and letters, some times punctuations as well. A DOI will keep the article forever retrievable in the event that a journal changes its name or ceases publishing. ISBN and ISSN don't need to be included in citation lists. However, a DOI, if it can be identified from the article that you downloaded, needs to be included in citation list. If the database didn't provide the DOI, you can check Crossref to look up the DOI. (Hint: When using Crossref, use the second option to "Search on article title", then enter the last name of the primary author, and enter the title of the article but do not enter the subtitle.)


An Example of DOI


Here are a few examples of DOI in citation lists.

DOI in APA Reference List

Herbst, D. M., Griffith, N. R., & Slama, K. M. (2004). Rodeo cowboys: Conforming to masculine norms and  
       help-seeking behavior for depression. Journal of Rural Mental Health, 38, 20-35. doi:10.1037/rmh0000008

DOI in MLA Reference List

Reinhart, Katrinka. "Rethinking Urbanism in the Early Bronze Age of China: The Role of Craft Specialists and Community
       Politics in the Social Construction of Yanshi Shangcheng." Archeological Research in Asia, vol. 14, pp. 106-120.

DOI in Chicago Style Reference List

Peltonen, Kirsi, Noora Ellonen, Helmer B. Larsen, and Karin Helweg-Larsen. “Parental Violence and Adolescent Mental Health.” European Child & Adolescent Psychiatry 19, no. 11 (2010): 813-822. doi: 10.1007/s00787-010-0130-8.

Acceptable DOI Format in Citation

Unacceptable DOI Format in Citation


Note: In old way, a DOI number should be preceded by "doi:"  According to recent change, "" is preferred by publishers as prefix. Both are the right formats. To be safe, take and include what you directly see from the article. In APA style, no period is used at the end of the doi; in MLA and Chicago, the doi is ended with a period.

Persistent Link

The link in the address bar or the Universal Resource Locator (URL) are not permanent gateways pointing to electronic resources, especially when using a subscription database. To cite an electronic resource and indicate its permanent location in the database, ejournal or ebook, you need its Persistent Link, which is also called Permanent Link or Stable URL. When you want to save a link to an article, make sure that you take its Persistent Link. Do not copy and paste links from the address bar. Here is an example from JSTOR:

An Example of Persistent Link in JSTOR

You can also create a Persistent Link when using OneSearch. Below is the Persistent Link for the same article in OneSearch. You will notice that the digital ID number in JSTOR is part of the link that OneSearch automatically generates.


An Example of Persistent Link in OneSearch



ORCID stands for Open Researcher and Contributor ID. ORCIDs are unique, persistent, alphanumeric digital identifiers provided to individual researchers (not materials) to identify and represent themselves, ensuring their online digital identities are recognizable and transferrable. ORCIDs can be used in conjunction with other professional information, such as affiliations, educational background, employment history, and scholarly achievements and activities. A typical example could be An ORCID is a researcher's digital identity, which does not need to be included in the reference list. Some publishers may request that researchers submit their ORCIDs along with manuscripts.

Asst Prof/Head of Cataloging & Serials

Junli Diao's picture
Junli Diao
94 - 20 Guy R. Brewer Blvd., Jamaica, NY 11451