APA reference list example: Online audio or video file. The writer/presenter is listed by last name and initial, followed by the abbreviation n period d period (for “no date”) in parentheses: Chomsky, N. (n period d period). The title is The new imperialism. It is followed by no punctuation. The label is listed in brackets, followed by a period: [Audio file]. The words “Retrieved from” are followed by the URL, with no period at the end: http://www.rhapsody.com/noamchomsky