Cita APA (7a ed.)

Whitney, N., & Branton, L. (1977). The sky's the limit. Heinemann Educational Books.

Cita Chicago Style (17a ed.)

Whitney, Norman, y Leslie Branton. The Sky's the Limit. London: Heinemann Educational Books, 1977.

Cita MLA (9a ed.)

Whitney, Norman, y Leslie Branton. The Sky's the Limit. Heinemann Educational Books, 1977.