Citing Medicine provides assistance to authors in compiling lists of references for their publications, to editors in revising such lists, to publishers in setting reference standards for their authors and editors, and to librarians and others in formatting bibliographic citations.

If you wish to cite this publication, please use the following format:

• Patrias K. Citing medicine: the NLM style guide for authors, editors, and publishers [Internet]. 2nd ed. Wendling DL, technical editor. Bethesda (MD): National Library of Medicine (US); 2007 -    [updated 2015 Oct 2; cited Year Month Day]. Available from: http://www.nlm.nih.gov/citingmedicine

Background

Citing Medicine updates and supersedes two previous National Library of Medicine publications:

• Patrias K. National Library of Medicine recommended formats for bibliographic citation [Internet]. Bethesda (MD): The Library; 1991. Available from: http://www.nlm.nih.gov/pubs/formats/recommendedformats.pdf
• Patrias K. National Library of Medicine recommended formats for bibliographic citation. Supplement: Internet formats [Internet]. Bethesda (MD): The Library; 2001 Jul. Available from: http://www.nlm.nih.gov/pubs/formats/internet.pdf

As in the previous edition, it is not the purpose of the National Library of Medicine to create a new bibliographic standard with this publication, but rather to apply existing standards to complex biomedical material. NLM is an active member of the National Information Standards Organization (NISO) and its various published standards have been adopted for the Library's MEDLINE/PubMed database. This publication thus also serves to document the Library's rules for the structure of journal citations.

Instructions for citing a variety of print publications, audiovisual material such as videocassettes, CD-ROMs and DVDs, items found on the Internet, and unpublished material such as papers presented at meetings are found in Citing Medicine. Be aware, however, that individual publishers may not accept references to all the types of items presented here. Papers that have been accepted for publication but not yet published, papers or abstracts of papers that were never published, and written personal communication such as letters or e-mails in particular may not be approved. Consult the instructions to authors for the particular publisher.

Source Material

Three major sources are utilized in compiling Citing Medicine: the MEDLARS Indexing Manual of the National Library of Medicine (NLM); pertinent NISO standards, primarily ANSI/NISO Z39.29-2005 Bibliographic References (http://www.niso.org/); and relevant standards from the International Organization for Standardization (ISO), primarily ISO 690 Documentation - Bibliographic References (http://www.iso.org/).

In applying the rules presented by these three sources, the MEDLARS Indexing Manual is given preference. The NLM format as shown in this publication follows NISO in principle, but certain deviations are made, primarily in the interest of saving labor in producing MEDLINE/PubMed. Those familiar with the Manual are aware that its scope is limited to journal articles. However, if a precedent was established by the Manual, as for example with pagination and dates, this precedent is carried over into other types of bibliographic material. If no NLM precedent is available, then the NISO and ISO standards are followed.

Users should note that bibliography is not the same as cataloging. The references found in this publication will therefore not agree with the records found in the Library's LocatorPlus and NLM Catalog databases.

Structure

Citing Medicine is divided into 26 chapters, each one representing a separate bibliographic format. Formats range from print publications such as books and journals to blogs and wikis on the Internet. Both published and unpublished material is included. Two new chapters have been added since the previous edition: Manuscripts (Chapter 14) and Prints and Photographs (Chapter 17).

Each chapter has three distinct sections: Sample Citation and Introduction, Citation Rules, and Examples of Citations. The sample citation is a diagram with labels for all of the parts of a citation and includes punctuation; the introduction provides information on the primary factors in citing the particular format. We believe that this section will satisfy the needs of many users who need only cursory information.

Section two, Citation Rules, gives step-by-step instructions for constructing a citation. Each part of a citation is presented in the order in which it would appear in a reference. For each part, General Rules provide basic information (for example, authors should be listed surname first) and Specific Rules cover special situations, such as handling organizations as author. Each part is also labeled either a required or optional component of a reference. Required parts are those necessary to uniquely identify an item; optional parts provide additional information to assist in locating an item and/or deciding if it is worthwhile to obtain an item. For example, pagination is optional for books, but the length of a book usually can provide an indication of the coverage of the subject.

Finally, the third section, Examples of Citations, includes sample citations that illustrate the rules given in section two. These examples are obtained primarily from the NLM collection and a variety of online databases. Because of the large volume of references needed, it is not possible to verify all information with the original, as an author would for a list of references. All the URLs (Uniform Resource Locators) used for Internet references were valid at the date of citation shown, but their current validity cannot be assured.

All the references in the Examples section represent actual publications. However, some license is taken in the examples for the Specific Rules. In an effort to illustrate unusual situations that might occur for which no actual examples can be found, citation fragments are created.

Citing Medicine also contains six appendixes. Appendixes A through D consist of summary information from relevant ISO and other standards to assist the user. Appendix E contains official US and Canadian abbreviations for the names of states, provinces, and territories. Links from the Specific Rules to these appendixes are made throughout the publication. Appendix F contains exceptions to NISO standards and Citing Medicine for nine citation elements found in Chapter 1A Journal Articles and Chapter 23A Journal Articles on the Internet

Application

Although this publication permits a number of variations in format, the user should be consistent in applying them throughout a reference list. For example, if the full journal title is used instead of the title abbreviation in one reference, it should be used in all journal article references.

The user may also wish to consider the purpose for which the references are being created. For example, Citing Medicine permits the publisher name to be given in an abbreviated format if the author and publisher are the same. Thus if the University of Virginia is the author, it may be abbreviated to "The University" as publisher. However, if the references will be used in a database in which the publisher name is searchable, the name should be given in full in both places.

When citing any type of format, one rule is primary: an author should never place in a reference list a document that he or she has not seen. The medical literature is full of references that have been cited from other references, serving only to perpetuate erroneous information. If a document is important enough to be cited in a reference list, it is equally important to examine the original for citation information.

Internet publication has created the new complication of citing the version seen. Many publishers are producing documents such as books and journals in multiple versions - in print, CD-ROM or DVD, and the Internet. These versions may appear identical in content, but because errors or other changes may have been introduced in the conversion from one format to another, they may in fact differ in significant ways. Also, once a document is in electronic format, changes and additions can easily be made that further distance the content from the more fixed print version. Always cite the specific version seen. In particular, do not cite a document as if it were a print one when the electronic version was used.

Reference Lists Versus In-Text References

References are presented in two ways in medical publications. At the end of a journal article, book, or book chapter, all of the references that contributed to the work are presented in a list called references, end references, literature cited, or bibliography. Within the text of a publication, individual references are presented in an abbreviated format that refers back to the list. These abbreviated references within the text are called "in-text references."

Three major systems of in-text references are used by medical publishers: citation-sequence, citation-name, and name-year. See Scientific Style and Format (7th ed. Reston (VA): Council of Science Editors; 2006) for a detailed discussion of all three systems.

In the citation-sequence system, numbers are used to refer to the reference list. References are numbered in the list in the order they first appear in the text. For example, if a reference by Zelinski is the first one referred to in the text, then the Zelinski reference is number one in the list.

In the citation-name system, numbers are also used in the text to refer to the reference list. However, the references in the list are numbered in alphabetical order by author. Thus a reference authored by Adam would be number 1, by Baker number 2, etc. These numbers are used in the text regardless of the order in which they appear.

Finally, in the name-year system, in-text references consist of the surname of the author and the year of publication, usually enclosed in parentheses, such as (Smith 2006). The list of references is ordered first by author, then by year.

Both the citation-sequence and citation-name systems format parts of references in the same order that they are found in Citing Medicine. In the name-year system the date of publication is taken out of order and placed after the author or after the title if there is no author. To accommodate those users who prefer using the name-year system, instructions are provided in each chapter in the Special Rules under "Options for date of publication."

The Library intends Citing Medicine to be an evolving publication. Join the publication’s e-mail list at http://list.nih.gov/archives/citingmed.html to learn of additions and changes. Your comments and suggestions are welcome. Please submit them to us via the National Library of Medicine's Contact Form.

Acknowledgments

The author wishes to acknowledge the many individuals who worked so tirelessly to bring this entire huge publication project to fruition:

Dan Wendling - for his electronic publishing expertise.

Lori Klein - for leading the editorial review process.

Marcia Zorn - for her review and suggestions for chapter readability.

Terry Ahmed, Mary Conway, Lori Klein, Carolyn Willard, and Marcia Zorn - for their line-by-line proofread of the chapters.

Terry Ahmed, Cynthia Burke, Mary Conway, Bill Feidt (National Agricultural Library (retired)), Ron Gordner, Jenny Heiland, Lori Klein, Andrew Plumer, Barbara Slavinski (NLM Guest Researcher), Carolyn Willard, and Marcia Zorn - for their resourcefulness in locating many of the examples provided.

Brooke Dine and Simon Vann - for their HTML/XML expertise.

Peggy Morrison (Hendrix College, Conway, Arkansas) - for consultation with citation problems.

Joyce Backus - for oversight of the project.