LUBIS, Y. (1988). Developing communicative proficiency in the english asa foreign language (EFL) class. Depdikbud.
Lua i Stíl Chicago (17ú heag.)LUBIS, Yusnaini. Developing Communicative Proficiency in the English Asa Foreign Language (EFL) Class. Jakarta: Depdikbud, 1988.
Lua MLA (9ú heag.)LUBIS, Yusnaini. Developing Communicative Proficiency in the English Asa Foreign Language (EFL) Class. Depdikbud, 1988.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.