Citing References in Scientific Research Papers
Compiled by Timothy T. Allen, revised 2000. This paper greatly expands upon a handout originally prepared by an unknown author for distribution to students in introductory earth science courses at Dartmouth College. The work is presented here without copyright, although acknowledgement is (of course) appreciated. This document is also available in in Adobe Acrobat Format
It is important to properly and appropriately cite references in scientific research papers in order to acknowledge your sources and give credit where credit is due. Science moves forward only by building upon the work of others. There are, however, other reasons for citing references in scientific research papers. Citations to appropriate sources show that you've done your homework and are aware of the background and context into which your work fits, and they help lend validity to your arguments. Reference citations also provide avenues for interested readers to follow up on aspects of your work -- they help weave the web of science. You may wish to include citations for sources that add relevant information to your own work, or that present alternate views.
The reference citation style described here is a version of the "Author, Date" scientific style, adapted from Hansen (1991) and the Council of Biology Editors (1994). Harnack & Kleppinger (2000) have adapted "CBE style" to cite and document online sources.
When to Cite References in Scientific Research Papers
You should acknowledge a source any time (and every time) you use a fact or an idea that you obtained from that source. Thus, clearly, you need to cite sources for all direct quotations. But you also need to cite sources from which you paraphrase or summarize facts or ideas -- whether you've put the fact or idea into your own words or not, you got the fact or idea from somebody else and you need to give them proper acknowledgement (even if an idea might be considered "common knowledge," but you didn't know it until you found it in a particular source).Sources that need to be acknowledged are not limited to books and journal articles, but include internet sites, computer software, written and e-mail correspondence, even verbal conversations with other people (in person or by telephone). All different kinds of sources must be acknowledged. Furthermore, if you use figures, illustrations, or graphical material, either directly or in modified form, that you did not yourself create or design, you need to acknowledge the sources of those figures.
Details of Citing References in your Text
When you cite a reference in your text you should use one of the following three formats:
(1) Mention the author by last name in the sentence and then give the year of the publication in parenthesis:
According to Rodgers (1983), the Appalachian mountains were formed in three events.
(2) Give the facts or ideas mentioned by the author and then attribute these facts or ideas by putting both his or her last name and the date in parenthesis:
The first of the three events occurred in the Ordovician, the second in the Devonian, and the third in the Carboniferous and Permian Periods (Rodgers, 1983).
(3) Quote the author exactly--be sure to put the quoted phrase between quotation marks--and then list the author's name, the date, and the page number in parenthesis:
"All the climaxes produced mountainous islands or highlands that shed vast amounts of debris westward to form clastic wedges or delta complexes on the continental margin." (Rodgers, 1983, p. 229).
You only need to include the page number in the citation if you are quoting directly, or if the source is very long and the specific fact or idea you are citing can only be found on a specific page. Direct quotations that are more than 4 lines long should be set off from the rest of your paper by use of narrower margins and single spaced lines.
If you have more than one source by the same author published in the same year, distinguish them both in the in-text citation and in the reference list, by appending the letters a, b, c... to the year, in the order in which the different references appear in your paper. (For example: Allen 1996a, 1996b.)
If the reference you are citing has two authors, use the following format:
Periods of glaciation have a large effect on sea level (Ingmanson and Wallace, 1985).
If the reference you are citing has more than two authors, use the following format:
Hot spots are formed by the drift of plates over mantle plumes (Vink et al., 1985).
If your source of information is from a personal verbal communication, you would use the following format for the first citation from that person:
It is possible to correct the raw dD values measured on the mass spectrometer (Mark Conrad, Lawrence-Berkeley National Lab, personal communication).
Later citations to the same person can be shortened, as in:
The reproducibility of dD determined by these methods is thought to be about +/- 2 per mil (Conrad, personal communication).
If your source of information is from written correspondence (a letter or e-mail), you would substitute the word "written" for the word "personal" above, and you would add the date of the letter (if dated). Personal communications are generally not included in the References Cited or Bibliography section, although unpublished papers, reports or manuscripts should be.
If your source of information has no individual identifiable author, use the name of the organization to which the work can be attributed in place of the author's name:
The reference citation style described here is a version of the "Author, Date" scientific style, adapted from the Council of Biology Editors (1994).
For internet sources without any identifiable author or date, simply use the URL address as the in-text citation:
As New England is located at the convergence of several distinct storm tracks (http://www.mountwashington.org/mtw_mtn.htm), we expect to find clear differences in isotopic composition among seasons and potentially among different rain storm events (Fig. 1).
Such a source would be omitted from your References Cited or Bibliography section.
Details of Formatting Reference Lists
Your list of References Cited should include all of the references you cited in your paper, and no more! It should be arranged in alphabetical order by the last name of the first author. If you have more than one entry by the same author, they should be further ordered by increasing publication date (more recent papers last). If you have multiple sources from a single author published in the same year, distinguish them both in the in-text citation and in the reference list, by appending the letters a, b, c... to the year, in the order in which the different references appear in your paper. (For example: Allen 1996a, 1996b.) You should include enough information that your readers will be able to find these sources on their own. The exact format is not critical, but consistency and completeness is. Reference lists are generally reverse-indented--this just helps the reader to find references to specific authors that much faster. Follow the examples given below and you will be all set.
- For Books
- List all authors by last name and initials, separated by commas if there are more than two authors. Put an "and" before the last author in the list. Then put the year of publication, the title of the book (in italics if possible), the publisher, the city, and the number of pages in the book.
Gould, S. J., 1983, Hen's Teeth and Horse's Toes, W. W. Norton, New York City, 413 p.Two or more authors:
Ingmanson, D. E. and Wallace, W. J., 1985, Oceanography: An Introduction, Wadsworth, Belmont, CA, 530 p.
- For Articles or Chapters with separate authors from a Book or Compilation
- List the author(s) of the article using the same format given above for books, then give the year, the title of the article or chapter (no quotes, italics or underlines), then the name(s) of the editor(s) of the book or compilation, followed by "ed." or "eds.". Then put the title of the book (in italics if possible), the publisher, the city, and the page numbers where the article can be found:
Rodgers, J., 1983, The life history of a mountain range-- Appalachians, in Hsu, K. J., ed., Mountain Building Processes, Academic Press, Orlando, p. 229-243.
- For an Article from a Journal or Magazine
- List the author(s) of the article using the same format given above for books, then give the year, the title of the article or chapter (no quotes, italics or underlines), then the title of the journal or magazine (in italics if possible), the volume number of the journal (do not use the publication date), and page numbers where the article can be found:
Maddox, J., 1987, The great ozone controversy, Nature, v. 329, p. 101.Two or more authors:
Vink, G. E., Morgan, W. J., and Vogt, P. R., 1985, The Earth's hot spots, Scientific American, v. 252, p. 50- 57.
- For Internet sources
- Give the author's last name and initials (if known) and the date of publication (or last modification). Next, list the full title of the work (e.g. the specific web page), and then the title of the complete work or site (if applicable) in italics (if possible). Include any version or file numbers, enclosed in parentheses. Most important, provide the full URL to the resource, including the protocol, host address, and the complete path or directories necessary to access the document. Be sure to spell this out exactly! (best to use an electronic "copy" from the "location" box of your browser and "paste" into your word processor). Finally specify the date that you last accessed the site, enclosed in parentheses.
Focazio, M.J., Welch, A.H., Watkins, S.A., Helsel, D.R., and Horn, M.A., 1999, A retrospective analysis on the occurrence of arsenic in ground-water resources of the United States and limitations in drinking-water-supply characterizations, U.S. Geological Survey Water-Resources Investigation Report 99-4279, http://co.water.usgs.gov/trace/pubs/wrir-99-4279/ (August 1, 2000)
Adapt these formats as necessary for other types of sources, including unpublished reports or manuscripts -- just be sure to include sufficient information that your readers could find or obtain these sources themselves, if need be.
Further information can be found by consulting Hansen (1991), Council of Biology Editors (1994), and Harnack & Kleppinger (2000), particularly their chapter on Using CBE Style to Cite and Document Sources.
References Cited (in this document)
Council of Biology Editors, 1994, Scientific style and format: the CBE manual for authors, editors, and publishers, 6th edition, Cambridge University Press, New York. 825 p.
Hansen, W. R. (editor), 1991, Suggestions to authors of the reports of the United States Geological Survey, 7th edition, U. S. Government Printing Office, Washington, D. C., 311 p.
Harnack, A., and Kleppinger, E., 2000, Online! A reference guide to using internet sources, Bedford/St. Martin's, http://www.bedfordstmartins.com/online/index.html (August 1, 2000).
Last modified August 7, 2000
APA Web Site Citation
Web sites do not include subscription databases
- Examples are not double-spaced, but your References list should be double-spaced
- Examples do not show indented lines after the first line, but yours should be indented
- Omit any information not found (author, organizational sponsor, date published or updated, etc.).
There are three elements absolutely necessary for an web site citation:
- Name (or title) of site
- Date of retrieval if web site is not Authoritative
- URL of Homepage (Internet address) (If hard to find like on a government website, complete URL can be used)
Author's Last Name, First Initial. Middle Initial. (Date of Publication or Update). Title of work. Retrieved Month Day, Year, from URL from Homepage
Basements and crawl spaces. (2002, June 23). Retrieved from http://www.hud.gov/ offices/hsg/sfh/ref/sfhp1-25.cfm
Build smarter with alternative materials. (n.d.). Retrieved June 15, 2002, from http://www.build-smarter.com/
Clemens, S. L. (n.d.). Roughing it. Retrieved from http://lcweb2.loc.gov/cgi-in/query/r?ammem/calbkbib:@field(TITLE+@band(Roughing+it.+))
E.I. du Pont de Nemours and Company. (2002). DuPont Tyvek®. Retrieved June 15, 2002, from http://www.tyvek.com/
Hacken, R. (n.d.). Home page. Retrieved January 23, 2002, from http://www.lib.byu.edu/estu/
7-step home construction plan. (n.d.). Retrieved June 15, 2002, from http/www.plansforme.com/ownmyhome/home_building/index.html
Seville, C. (2001, January 25). Finish materials in design/build. Retrieved from http://www.housingzone.com/topics/hz/cmaterials/hz01aa604.asp
Study skills self-help information. (n.d.). Retrieved December 1, 2001, from http://www.ucc.vt.edu/stdysk/stdyhlp.html
Willett, P., ed. (1997, April). Victorian women writers project. Retrieved from http://www.indiana.edu/~letrs/vwwp/nesbit/ballsoc.html