Fucilla, Joseph G.
Follett Publishing Company, 1964
Buku Referensi
Payne, Stanley G.
W.W. Norton, 1970
Buku Teks SO
Cronin, A.J.
Bantam Books, 1957
Buku Teks SO
Eckersley, C. E. (Charles Ewart), 1892-1967
Longmans, Green and Co., 1953
Buku Referensi
London; Cassell LTD., 1978
Buku Referensi