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
Sargent, Lyman Tower, author
Wadsorth Thompson Learning, 2003
Buku Teks
Routledge, 1993
Buku Teks