Citing the Federal Acquisition Regulation is a two-part system. In your text, cite according to the Publication Manual of the American Psychological Association, but in your references section, use “The Bluebook: A Uniform System of Citation.” The Federal Acquisition Regulation is part of the code of federal regulations and is cited as such.
In text, cite the name of the regulation and the year the regulation was last updated. "According to the definition, kickbacks include anything of value (Federal Acquisition Regulation, 2014).” Or, “The definitions section of the Federal Acquisition Regulation defines kickbacks (2014).” Generally, spell out titles, but if the name is long and cumbersome and the abbreviation is readily understood, you may abbreviate the second and subsequent citations. In the first citation, place the abbreviation in brackets after the title and before the date: “(Federal Acquisition Regulation [FAR], 2014)”
In the references section, cite according to rule 14.2 of the Bluebook, but include the title of the regulation. Cite the title of the regulation, the title number, the abbreviation "C.F.R.", the section symbol, the section number, and the effective date of the C.F.R. in parentheses. Always cite the regulation in effect, unless you are citing an older C.F.R. as history. When citing federal regulations, do not provide the URL or other location identifier. For example, “Federal Acquisition Regulation, 48 C.F.R. § 3.502-1 (2014).“
Citing Proposed Regulations
A proposed rule or one not yet promulgated into the C.F.R. is cited to the “Federal Register” in this order: title as listed in the Register, “Fed. Reg.,” volume number, page number(s) and the publication month, day and year, of the issue of the Federal Register that contains the notification. If the regulation is to be codified in the C.F.R., the words “to be codified,” and the the section of the C.F.R. to be amended is included in second parentheses, with a space between the two parentheses. Use the abbreviation for parts, or "pts.” instead of the section symbol. For example, “Federal Acquisition Regulation; FAR Case 2005-012, Combating Trafficking in Persons, 71 Fed. Reg. 2741-2746 (January 15, 2009) (to be codified at 48 C.F.R. pts. 12, 22, & 52)."