Pepper, Gerald L., author
McGraw-Hill, 1995
Buku Teks
Phillips, Gerald M., author
Macmillan, 1982
Buku Teks
Berko, Roy M, author
Houghton Miffiln, 2001
Buku Teks
March, James G., author
Wiley, 1950
Buku Teks
Hybels, Saundra, author
McGraw-Hill, 1992
Buku Teks