Denhardt, Robert B., author
Thomson, 2009
Buku Teks
Milakovich, Michael E., author
Wadsworth and Cengage Learning, 2009
Buku Teks
Nigro, Felix A., author
Harper and Row , 1977
Buku Teks
White, Leonard D., author
Macmillan, 1955
Buku Teks
Derbyshire, J. Denis, author
McGraw-Hill , 1979
Buku Teks