Citing Information Resources in the Biomedical Literature



When the word "citing" is used in this document, it refers to the numbers placed after facts in the body of the paper. When the word "references" or "resources" is used, it refers to the list at the end of the paper that indicate sources of information from which facts were derived.

General Questions about Citing

When should a resource be cited? If something is fairly well known about a drug, for example what disease state it is used for, it is not necessary to cite a source for the information. Any time you use numbers or introduce facts that are not well-known, you should cite the resource in which you found the information.

What if facts in a reference article are referenced? Always cite the reference where you obtained the information, even if that information is cited in the resource you used. For example, if you are reading a review and find some interesting numbers that you would like to add to your introduction, and the review cites those numbers as coming from a prior published study, then you will cite the review, not the prior published study. Why? Unless you pull and read the original study yourself, you cannot be entirely certain that the numbers in the review are accurately reported or that the writer of the review came to a valid conclusion. You therefore must cite only the information given you by the reviewer. If you pull the original study and read it yourself, then it is fine to cite the original study.

How should citations be ordered? Your first citation should be your first reference, your second citation the second reference, and so on. Do not present your references in the reference list in alphabetical order; this is routinely done in the social sciences literature but not the biomedical literature. Instead, the references should be presented in the order in which they appear in the text.

How are citations done in the biomedical literature? You will use citation numbers, rather than the first author's name and publication year, when citing information. The first author's name and year of publication are widely used in citations in the social science literature, but citation numbers are used in biomedical literature. Citation numbers should be superscripted like this,1 not in parentheses like this.(1) The citation number goes outside of punctuation like this,1 not inside of punctuation like this1. Citation numbers can either be placed in the middle of a sentence, immediately after the fact you presented, or at the end of the sentence which contains the fact. If you are citing several facts from the same source, your citation number will appear just once, at the end of the sentence containing the first fact from that source. However, if you present information from one resource, then information from a second resource, then more information from the first resource, you will need to cite the first resource both the first and second time you present facts from that resource.

All references should be listed at the end of the paper in a single list, titled "References." Footnoting is generally not done in the biomedical literature and so will not be an acceptable citation method for this paper.

Quoting versus Paraphrasing

In general, do not quote from papers when doing medical writing. Instead, paraphrase the concept in your own words and then cite the manuscript from which you learned the concept. The only time you will quote is if you interview a resource individual yourself, or if you are pointing out in an evaluation actual wording used by authors that you feel was misleading or indicated bias (and here you are presenting the authors’ wording as evidence). The University of Wisconsin at Madison's writing center has a good example of how different from the original text wording needs to be in order to be considered paraphrasing, rather than plagiarism.

Reference Formats For Specific Types of Publications

You are likely to have in high school learned the reference format advocated by the Modern Language Association (MLA) or American Library Association (ALA). In college classes, you may have had to use either the MLA or ALA reference styles or reference styles advocated by the Chicago Manual of Style, the American Psychological Association (APA), or the Council of Biology Editors (CBE). Now we're asking you to learn yet another style for use on your paper. This style was originally agreed on in 1994 by the International Committee of Medical Journal Editors. It has since been adopted by the National Library of Medicine (NLM) as their style guide. You will find that many biomedical journals use this citation format.

Journal articles
These are the articles that will make up the body of your drug information paper. You will also use this format for review articles you find in medical journals. The information for how to cite permutations of journal articles are all in the National Library of Medicine link on the PHARM 309 web page. You can find journal title abbreviations using PubMed's journal database function. Type in the full name of the journal and then use the abbreviation indicated in the "Title Abbreviation:" line.

Lastname INITIALS, Lastname INITIALS, Lastname INITIALS, et al. Title of article. Journal Title Abbr year;volume:beginning page number – ending page number.


  1. De Smet PAGM. Herbal remedies. N Engl J Med 2002;347:2046-56.
  2. Smith NL, Heckbert SR, Lemaitre RN, Reiner AP, Lumley T, Weiss NS, Larson EB, Rosendaal FR, Psaty BM. Esterified estrogens and conjugated equine estrogens and the risk of venous thrombosis. JAMA 2004;292:1581-7.

A note: pasting in citations directly from PubMed is problematic and not recommended.

Paper Textbook
The information for how to cite permutations of textbooks are all in the National Library of Medicine link on the PHARM 309 web page.

Lastname INITIALS, Lastname INITIALS, Lastname INITIALS, et al. Title of chapter. In: Lastname INITIALS, editors. Textbook title. Location: Publisher, year published: page number – ending page number.


  1. Fish DN, Sahai J. Urinary tract infections. In: Koda-Kimble MA, Young LY, editors. Applied therapeutics: the clinical use of drugs. Philadelphia (PA): Lippincott Williams, & Wilkins, 2001: 62-1 – 62-4.

Electronic textbooks, databases, and web sites
Use the format recommended by the National Library of Medicine. This format is listed below as is information addressing common questions. There is a pdf document published by NLM that has specific information, if you have the time to wade through it.

Lastname INITIALS, Lastname INITIALS. Title of article. [Internet] Location*: Publisher; ©year [date updated;date accessed]. Available from: paste internet address here.

  • *location = City (ST) or City (Country)
  • note: format for international dates, such as those you find from internet resources are YYYY Mon DD, e.g., 2005 Oct 5)


  1. Sobel JD, Kaye D. Urinary tract infections. In: Principles and practice of infectious diseases [Internet]. New York (NY): Churchill Livingston; c2000 [cited 2002 Oct 31]. Available from:
  2. Hooton TM, Stamm WE. Recurrent urinary tract infection. In: UpToDate [Internet]. Wellesley (MA): UpToDate, Inc; c2002 [updated 2001 Aug 16; cited 2002 Oct 31]. Available from:

Electronic Citation FAQs

What is the correct order to present information on an electronic resource? Per the National Library of Medicine recommendations, you should list information in the following order:

    • Author. Title. In: Textbook name. [Internet] Location: Publisher; copyright year [date updated;date accessed]. Available from: paste internet address here
    • Notice that the example above does not have a period at the end of it. This is because internet addresses never end with periods, so it would be confusing to the reader to put a period at the end of an internet address, and it would interfere with their ability to locate that web site, if they pasted the web address into the URL/address locator of a web browser.
    • The format for the date is always the 4-digit year first, then the first three letters of the month, then the day. Example: 2003 Oct 31
    • The format for the location is the city name, followed by the state or country in parentheses. For example, the location of this web site is Seattle (WA).

What if there doesn't appear to be an author? If there is no apparent author, then you can omit the author's name and start first with the title.

Do you have to write out an author's first name as well as the last name? It is fine to just use the author initials after the last name, for example, O'Sullivan TA.

How can you tell the title of the web page? If there doesn't seem to be an obvious title, look at the top of your browser window. You should see something that looks like this:

The "University of Washington" that you see at the top of the browser window is what the web page has been named.

What if it's not apparent who the publisher is? In this case it will take a bit of detective work on your part. Some web sites are company web sites that have been put together by a company, but the web address doesn't reflect this. A good example is AstraZeneca's web page for esomeprazole. The web address is, but the publisher is AstraZeneca. Some web sites have been put together by a single individual. In this case that individual is both the author and the publisher. If you do not find any information about who published the web site, then you're dealing with a web site you should not trust. Do not use such web sites to reference facts. The only use for such a web site is to use as an example of a poorly-done web site on the web resources assignment, and in this case you will want to mention in your explanation of why it's a poorly-done web site that the web site doesn't list the publisher.

What if you can't find the location of the publisher? First, do some detective work. Look at the "About us" or "Contact us" links. If the publisher appears to be a drug company, but you cannot see through any site links where that company is located, try looking on the main company web site (you may have to use an internet search engine to find the company's site). If the company has several listed locations, look for one designated as "corporate headquarters." If the company is multinational, you will list the corporate headquarters for the U.S. One example of a hard-to-identify location of a publisher is It took some careful detective work to determine that this web site had been put together by an employee of the H.J. Heinz company, and even more detective work to discover that this company is headquartered in Pittsburgh (PA).

What if you cannot find the copyright date? You should not use information from a web site that does not have a copyright date, because you will not know how old the information is. You may use such a site as an example of a poorly-done web site on the web resources assignment, and in this case you will want to mention in the explanation that the web site doesn't list the copyright date.

What if there is no date indicating when the site was last updated? In this case you will assume that the site has not been updated since the year indicated in the copyright. You will omit the update date and only include the date cited in brackets in your reference.

Could I see an example of a reference list for a drug information paper that I might right? Certainly. The following example could be a reference list for a drug information paper on the topic of drinking cranberry juiceto treat or prevent urinary tract infections.


  1. Sobel JD, Kaye D. Urinary tract infections. In: Mandel: Principles and Practice of Infectious Diseases [Internet]. New York (NY): Churchill Livingston; c2000 [cited 2005 Sep 26]. Available from:
  2. Hooton TM, Stamm WE. Recurrent urinary tract infection in women. In: UpToDate [Internet]. Wellesley (MA): UpToDate, Inc; c2005 [updated 2005 Feb 14; cited 2005 Sep 26]. Available from:
  3. Gingrich CL. Bacterial infections of the urinary tract in women. In: Rakel RE, Bope ET, eds. Conn's Current Therapy. [Internet] Philadelphia (PA): W.B. Saunders; c2005 [cited 2005 Sep 26]. Available from:
  4. Cranberry. In: Review of Natural Products. [Internet] St. Louis (MO): Facts and Comparisons; c2005 [updated 2005 Jul; cited 2005 Sep 26] Available from:
  5. Cranberry. In: Natural Medicines Comprehensive Database [Internet]. Stockton (CA):Therapeutic Research Faculty; c1995-2005 [cited 2005 Sep 26].Available from:
  6. Briggs S, Rouse JE. Cranberry. In: Alternative Medicine Evaluation [Internet]. Greenwood Village (CO): Thomson MICROMEDEX; c1974-2006 [cited 2005 Sep 26].Available at:
  7. Cranberry (Vaccinium macrocarpon) and Urinary Tract Infection. [Internet] Bethesda (MD): National Institutes of Health (US); c2003 [modified 2004 Feb 5; cited 2005 Sep 26]. Available at:
  8. Can your diet prevent a urinary tract infection? [Internet] Santa Fe (NM): Web-based Health Education Foundation; c2005. [upated 2003 Apr 17; cited 2005 Sep 26].
  9. Lowe FC, Fagleman E. Cranberry juice and urinary tract infections: what is the evidence? Urology 2001; 57:407-13. (PubMed)
  10. Kontiokari T, Sundqvist K, Nuutinen M, Pokka T, Koskela M, Uhari M. Randomised trial of cranberry-lingonberry juice and Lactobacillus GG drink for the prevention of urinary tract infections in women. BMJ 2001;322:1571-5. (Current Contents)
  11. Schlager TA, Anderson S, Trudell J, Hendley JO. Effect of cranberry juice on bacteriuria in children with neurogenic bladder receiving intermittent catheterization. J Pediatr 1999;135:698-702. (PubMed)
  12. Reid G, Hsiehl J, Potter P, Mighton J, Lam D, Warren D, Stephenson J. Cranberry juice consumption may reduce biofilms on uroepithelial cells: pilot study in spinal cord injured patients. Spinal Cord 2001;39: 26-30. (Current Contents)
  13. Avorn J, Monane M, Gurwitz JH, Glynn RJ, Choodnovskiy I, Lipsitz LA. Reduction of bacteriuria and pyuria after ingestion of cranberry juice. JAMA 1994;27:751-4. (PubMed)
  14. Terris MK, Issa MM, Tacker JR.Dietary supplementation with cranberry concentrate tablets may increase the risk of nephrolithiasis. Urology 2001;57:26-9. (EMBASE)

The first nine references provided general background information and were cited in the introduction. Note that references 7 and 8 are internet sites and are given as examples of the correct format for citing something located on the web. Reference 9 is a review article. The remaining five articles were studies and were outlined in the body of the paper.


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