Cita APA (7th ed.)

Humphrey, F. N., & Humphrey, J. H. (1989). Recreation: Current selected research. AMS Press.

Cita Chicago (17th ed.)

Humphrey, Fred N., i James H. Humphrey. Recreation: Current Selected Research. New York: AMS Press, 1989.

Cita MLA (9th ed.)

Humphrey, Fred N., i James H. Humphrey. Recreation: Current Selected Research. AMS Press, 1989.