Cita APA (7a ed.)

GREENALL, S., & SPRENGER, J. G. (1987). Horizons: : First Certificate. Heinemann Educational Books.

Cita Chicago Style (17a ed.)

GREENALL, Simon, y Judy Garton SPRENGER. Horizons: : First Certificate. London: Heinemann Educational Books, 1987.

Cita MLA (9a ed.)

GREENALL, Simon, y Judy Garton SPRENGER. Horizons: : First Certificate. Heinemann Educational Books, 1987.