Radley, P., Simons, D., & Campbell, C. (2009). Horizons. Oxford University Press.
Cita Chicago Style (17a ed.)Radley, Paul, Daniela Simons, y Colin Campbell. Horizons. Oxford: Oxford University Press, 2009.
Cita MLA (9a ed.)Radley, Paul, et al. Horizons. Oxford University Press, 2009.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.