Sargent, Lyman Tower, author
Erlangga, 1987
Buku Teks
Spanier, John W.
Praeger , 1967
Buku Teks
Coleman, Janet, author
Blackwell Publishers, Ltd, 2000
Buku Teks
Losco, Joseph, author
Radja Grafindo Persada, 2005
Buku Teks
Varma, S.P., author
Radja Grafindo Persada, 2003
Buku Teks