Ferrell, Wilfred A
Holt, Rinehart and Winston, 1978
Buku Teks SO
edited by George Arms, William M. Gibson and Louis G. Locke
St. Martin`s Press, 1978
Buku Teks SO
Jones, Edward Harrell, 1922-
Macmillan, 1968
Buku Teks SO
Kearns, Francis E.
Holt, Rinehart and Winston, 1970
Buku Teks SO
Macmillan, 1970
Buku Teks SO