Bell, Jeffrey A, author
Edinburgh University Press Ltd, 2016
Buku Teks
Rosenfeld, Isadore, author
Random House, 1996
Buku Referensi
Epping, Randy Charles, author
Vintage books, 1995
Buku Teks
Pavkov, Thomas W., author
McGraw-Hill, 2007
Buku Teks
Roman, Kenneth
St. Martin's Press , 1976
Buku Teks