Strearn, William T.
David & Charles, 1983
Buku Referensi
Short, Ema
Cambridge University Press, 2013
Buku Teks
Berlyn, Graeme P.
Iowa State University Press, 1976
Buku Teks
Balbach, Margaret
Brace Jovanovich College, 1991
Buku Teks
Plowden, C. Chicheley
George Allen and Unwin, 1972
Buku Teks