california state departement of educatio, 1956
Buku Teks
Rorden, Judith Waring, author
W.B. Saunders Company, 1987
Buku Teks
edited by David Lusted
Routledge, 1991
Buku Referensi
Aarons, Maureen, author
Routledge, 1992
Buku Referensi
Dacey, John S., author
Jossey-Bass Inc, 2000
Buku Teks