Christopherson, P. (1975). An advance English Grammer. Macmillan.
Lua i Stíl Chicago (17ú heag.)Christopherson, P. An Advance English Grammer. London: Macmillan, 1975.
Lua MLA (9ú heag.)Christopherson, P. An Advance English Grammer. Macmillan, 1975.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.