Purinton, Carl E.
The Ronald Press, 1961
Buku Teks SO
Fucilla, Joseph G.
Follett Publishing Company, 1964
Buku Referensi
Collier, Leonard Dawson
St. Paul's House Warwick Lane, 1973
Buku Teks SO
Payne, Stanley G.
W.W. Norton, 1970
Buku Teks SO
Cronin, A.J.
Bantam Books, 1957
Buku Teks SO