Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.


The basic tools you will need to research topics in biology, along with resources to help you write effectively within the discipline.

Why cite?

The primary reasons for citing sources in a research paper are to give credit to the authors whose work you have drawn upon and to allow readers to track down your sources, should they wish to explore further. There are many style guides for formatting citations and creating bibliographies. The AIP (the American Institute of Physics) Style Guide is frequently used in physics, but your professor may specify another format.

AIP Style

References should be set as a double-spaced list at the end of the text. The names, including initials, of all authors in each reference should be given (in the text, the use of “et al.” is permissible).

All references to books and journal articles, listed at the end of the paper, are to appear in only one of these three formats:

  1. By number, in order of first appearance, presenting the names of the authors, the journal name, volume, first page number only, and year. This paper will be listed as the 19th in the list of references and cited as 19 or Ref. 19:

    19L. M. Pecora, T. L. Carroll, G. A. Johnson, D.J. Mar, and J. F. Heagy, Chaos 7, 520 (1997).
  2. In alphabetical order according to the first author’s last name, including, in addition to the name, the title of the paper cited, journal name, volume, first and last page, and year. This paper will be cited as “Pecora et al. (1997).” 

    Pecora, L. M., Carroll, T. L., Johnson, G. A., Mar, D. J., and Heagy, J. F., “Fundamentals of synchronization in chaotic systems, concepts, and applications,” Chaos 7, 520–543 (1997).
  3. Alphabetically listed references (with full titles and page ranges) may be numbered according to their alphabetical order and cited by their number.

In-text Citation - General Rules

  • Cite references in numerical order
  • Numerals are to be placed after punctuation
  • Refer to authors in text by Surname / Family only
  • Use all authors names for a maximum of three authors. Where there are four or more authors use the first authors name and the expression "et al." ('et al'  is a Latin phrase meaning 'and others' ) eg. Smith et al.
  • Place citation numbers where they will not be confused for a different meaning:

                     A recent measurement2 of rv


                     A recent measurement of rv 2

Reference List - General Rules

  • References in the Reference list are ordered as they appear in the paper
  • The Reference list should start on a new page and should be a double-spaced numerical list
  • All references in the list must appear in the paper
  • Authors names are notated as they appear in their work
  • The use of "et al" is not used in the Reference list, here all authors are to be listed.

More Information about Style Format

Reference Management Tools

Resources for Scientific Writing

Help with Scientific Writing & Presenting