Paz, Mario
Van Nostrand Reinhold, 1986
Buku Teks SO
edited by Edwin H. Gaylord, Jr., Charles N. Gaylord
McGraw-Hill, 1980
Buku Referensi
edited by, Edwin H. Gaylord
McGraw-Hill, 1990
Buku Referensi
Williams, Alan
Kaplan Education, 2005
Buku Teks
edited by Edwin H. Gaylord, Jr., Charles N. Gaylord, James E. Stallmeyer.
McGraw-Hill, 1997
Buku Teks