Alden, John Richard
American Book Company, 1960
Buku Teks SO
Myers, Gustavus
Random House, 1943
Buku Teks
Kemmerer, Donald L.
Littlefield, Adams, 1956
Buku Teks SO
Rae, John B.
Mc Graw-Hill Book Company, 1949
Buku Teks
Risjord, Norman K.
Prentice-Hall, 1985
Buku Teks SO