There are two main citation styles used in engineering writing. American Psychological Association (APA) style and Modern Language Association (MLA) style are accepted formats for referencing sources. These styles govern both text references - parenthetical citations that immediately follow the text being referenced within a document - and the reference list at the end of the document. Your professor, or institution should be able to identify which citation style is desirable to be used in your document.

Tip: Microsoft Word (2007 and newer) will automatically insert properly formatted in-text citations and bibliography information. Just use the "References" tab and start by clicking "Manage Sources" to begin entering resource information.

For those of you citing your resources the old fashioned way, here are examples of the most commonly used citations in APA format for:

  • In-text citations
  • Creating a bibliography

Or visit, http://owl.english.purdue.edu/owl/section/2/, for additional information and more examples using both techniques.

Examples of in-text citations using APA format:

  • Book or article with one to two authors:

    (Arnold and Brookes, 2005).

    List each author by last name followed by the year the article was published.
  • Book or article with three to five authors:

    First citation: (Chase, Patterson, Adams, and Smith, 2007).
    Subsequent citations: (Chase et al., 2007).

    The first citation should list each author by last name followed by the year of publication. Subsequent citations can be written using the first author’s last name followed by “et al.” and the year. Note that “et al.” is an abbreviated form of the Latin phrase “et alia,” which means “and others.” Because the “al.” portion of the phrase is an abbreviation, you must always include the period.


  • Book or article by six or more authors:

    (Danielson et al., 2009).

    Use the first author’s name followed by “et al.” and the year the article was published.


  • Unknown author:

    (“Lean Manufacturing,” 2008).

    When the author is unknown, cite the source using its title captured in quotation marks, followed by the year of publication

Examples of how to create a bibliography using APA format:

  • Book or article with one to seven authors:

    Chase, F., Patterson, J., Adams, G., & Smith K. (2007). Industrial Engineering Applications in the Health Care Field. Journal of Ergonomics 11, 8-15.

    List each author by last name followed by the year the article was published in parentheses. The title is then listed in italics or quotes followed by the volume number and pages used.
  • Book or article more than seven authors:

    James, L., Roberts, S., Herrick, R., Johnston, E., Brown, N., Parker, B., … Yoder, R. (2004). An Engineering Solution to Waste Water Treatment Problems. International Journal of Engineering 15, 33-40.

    Note: List the first six authors followed by an ellipsis (...) with no ampersand (&)
  • Unknown author:

    “Lean Manufacturing.” (2008). Journal of Engineering Education. 22, 18-24.