Ramsey, William L., author
Holt, Rinehart and Winston, 1961
Buku Teks
McConnell, David, author
McGraw-Hill, 2010
Buku Teks
Bishop, Margaret S.
Charies E Mernill, 1976
Buku Teks
Owen, Claudia, author
Brooks/Cole Cengage Learning, 2010
Buku Teks
Williams, Peter J
Longman, 1982
Buku Teks