Radley, P., Simons, D., & Campbell, C. (2009). Horizons. Oxford University Press.
Lua i Stíl Chicago (17ú heag.)Radley, Paul, Daniela Simons, agus Colin Campbell. Horizons. Oxford: Oxford University Press, 2009.
Lua MLA (9ú heag.)Radley, Paul, et al. Horizons. Oxford University Press, 2009.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.