Collier, Leonard Dawson, author
St. Paul's House Warwick Lane, 1973
Buku Teks
Fucilla, Joseph G., author
Follett Publishing Company, 1964
Buku Referensi
Payne, Stanley G., author
W.W. Norton, 1970
Buku Teks
Eckersley, C. E. (Charles Ewart), 1892-1967, author
Longmans, Green and Co., 1953
Buku Referensi
London; Cassell LTD., 1978
Buku Referensi