Roberts, P. (1954). Understanding grammar. Harper.
Lua i Stíl Chicago (17ú heag.)Roberts, Paul. Understanding Grammar. New York: Harper, 1954.
Lua MLA (9ú heag.)Roberts, Paul. Understanding Grammar. Harper, 1954.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.