Cita APA (7a ed.)

Humphrey, J. H., & Humphrey, F. N. (1991). Recreation: Current selected research. Ams Press.

Cita Chicago Style (17a ed.)

Humphrey, James Harry, y Fred N. Humphrey. Recreation: Current Selected Research. New York: Ams Press, 1991.

Cita MLA (9a ed.)

Humphrey, James Harry, y Fred N. Humphrey. Recreation: Current Selected Research. Ams Press, 1991.