Combs, Arthur W.
Alyn and bacan , 1970
Buku Teks
Lewis, Harold, author
Lois and Samuel Silberman Fund, 1982
Buku Teks
Hawkins, Peter, author
Open University Press, 2005
Buku Teks
Corey, Gerald, author
Brooks/Cole Publishing, 1998
Buku Teks
Barsky, Allan Edward, author
Oxford University Press, 2017
Buku Teks