Parker, R.H.
Penguin Books, 1972
Buku Teks SO
Foster, Louis O.
Chelton, 1961
Buku Teks SO
Budd, Thomas A.
Alexander Hamilton Institute, 1961
Buku Teks SO
White, Gerald I.
John Wiley & Sons, 1994
Buku Teks
Friedlob, G. Thomas
Barron's Educational Series, 1991
Buku Teks SO