Powell, L. S. (1969). Communication and learning. Pitman.
Lua i Stíl Chicago (17ú heag.)Powell, Leonard Sutherland. Communication and Learning. London: Pitman, 1969.
Lua MLA (8ú heag.)Powell, Leonard Sutherland. Communication and Learning. Pitman, 1969.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.