APA (7th ed.) Citation

Adams, D. (1983). The hitchhiker's trilogy (Omnibus ed., 1st ed.). Harmony Books.

Chicago Style (17th ed.) Citation

Adams, Douglas. The Hitchhiker's Trilogy. Omnibus ed., 1st ed. New York: Harmony Books, 1983.

MLA (9th ed.) Citation

Adams, Douglas. The Hitchhiker's Trilogy. Omnibus ed., 1st ed. Harmony Books, 1983.

Warning: These citations may not always be 100% accurate.