APA reference list example: Online book. The author is listed by last name and initial: Adams, B. The year is listed in parentheses, followed by a period: (2004). The book title is italicized and is followed by a period: The theory of social revolutions. The words “Retrieved from”are followed by the UR, with no period at the end: http://www.gutenberg.org/catalog/world/readfile?fk_files=44092 The original date of publication is listed in parentheses, with no period at the end: (Original work published 1913)