edited by Otis W. Freeman and John W. Morris
McGraw-Hill, 1958
Buku Teks SO
Pounds, Norman J. G.
Silver Burdett, 1980
Buku Teks SO
edited by Otis W. Freeman and John W. Morris
McGraw-Hill, 1958
Buku Teks SO
Funk & Wagnalls, 2000,
Buku Referensi
by Christopher L. Salter ... [et al.]
Saunders College Publishing, 2000
Buku Teks SO