A date is one of the most critical elements of a reference in an academic paper. It is particularly vital in a periodical reference -- searching for a specific newspaper article without knowing the date on which it was published could be a laborious task. Nevertheless, sources without stated publication dates abound, and you should not discount a valuable source for this common omission. The American Psychological Association and Modern Language Association style guides prescribe remedies for unknown years, enabling you to craft the most thorough references possible.
Unknown Publication Date
While you can skip some parts of a reference, such as volume or issue numbers, if this relevant information is unknown, you must include a date entry in your reference even if you do not know the publication date. Both APA and MLA instruct writers to replace a missing date with the abbreviation “n.d.” Enter it in the same position in the reference in which you would type a known date. In APA references, insert the abbreviation between the parentheses that follow the author's name; in MLA references, insert the abbreviation before the medium of publication. For example:
APA: McCandless, B. II. (n.d.) Serving as CAPCOM for the moon landing. Retrieved from http://nasa.gov/apollo11at40/
MLA: McCandless, Bruce II. “Serving as CAPCOM for the Moon Landing.” NASA Education (italicized). NASA, n.d. Web. 20 July, 2013.
Month and Date without Year
Occasionally, blog posts have months and dates but not years. Similarly, you may refer to an old magazine or newspaper article for which you can only find the month and date of publication. In these situations, cite the known pieces of the publication date. Even if the month and date alone cannot help the reader locate a source, they can help her identify the correct post or article if she locates it with the other information you cite. Enter the month and date exactly as you would in a complete APA or MLA date entry, but remove any spacing or punctuation that relates to the year. In APA references, spell out the month immediately after the open parenthesis and then enter the date in Arabic numerals; in MLA references, enter the date in Arabic numerals followed by the abbreviated month. For example:
APA: McCandless, B. II. (April 20). Serving as CAPCOM for the moon landing. Retrieved from http://nasa.gov/apollo11at40/
MLA: McCandless, Bruce II. “Serving as CAPCOM for the Moon Landing.” NASA Education (italicized). NASA, 20 Apr. Web. 20 July, 2013.
MLA uses an author-page format for in-text citations. So, an unknown year will not affect an MLA in-text citation. APA uses an author-year format for in-text citations. Insert the abbreviation “n.d.” in place of an unknown year to maintain this format, even if you have a month and date for the source in your reference list. There is one exception: an in-text citation for personal correspondence, which you do not include in an APA reference list. When citing correspondence in the text, replace a completely unknown date with “n.d.” If you have a month and date, include them in the citation. Spell out the month as you would in a complete date citation. For example:
APA: (McCandless, n.d.)
APA: (McCandless, personal communication, April 20)
Other Identifying Information
Take time to determine any other numerical identifying information for the source, such as volume, issue or edition numbers. While that information is slightly less important in references that have complete date entries, those numbers may be very helpful for a reader who is trying to locate a source without a known publication year.
The most significant quality of a reference is that it is functional. Each reference should lead your reader to an accessible, published copy of your source. While APA and MLA encourage writers to cite a source's original publication whenever possible, you may need to ignore that rule if you are referencing a year-less source that you found in a secondary publication. For example, if you referenced a newspaper article that you found excerpted in a book, both style guides instruct you to cite the original publication of the article not the reprinted version in the book. If the book did not note the article's publication date and you could not locate another copy of the article, you could cite the original and include “n.d.” for the date entry. However, that reference would probably not be functional, making it impossible for your instructor to verify any quotations or facts that you attributed to that source. In a situation like that, ignore the rule about citing original sources and cite the book in which you found the article. APA and MLA rules for citing an article in a book require you to include identifying information for the article and book. A reference that included the article and the book may deviate from a cardinal citation rule but it would still be complete and, most importantly, it would be functional.