Fatzinger, James A. S.
Pearson-Prentice Hall, 2004
Buku Teks
Edwards, Harry J.
McGraw-Hill, 1986
Buku Teks
Liebing, Ralph W.
John Wiley & Sons, 1982
Buku Teks
Emmitt, stephen
Wiley-Blackwell, 2010
Buku Teks
Alexander, Christopher
Oxford University Press, 1977
Buku Referensi