Budd, Thomas A.
Alexander Hamilton Institute, 1961
Buku Teks SO
Hills, George S.
Garland Pubishing, 1982
Buku Teks
White, Gerald I.
John Wiley & Sons, 1994
Buku Teks
Friedlob, G. Thomas
Barron's Educational Series, 1991
Buku Teks SO
Fraser, Lyn M.
Prentice-Hall International, 1995
Buku Teks SO