Berry, George Ricker, author
Chicago, Fallet Publishing, 1962
Buku Referensi
New Canada Publications, 1980
Buku Teks
New Canada Publications, 1982
Buku Teks
Umar Junus, author
Universiti Malaya, 1974
Buku Teks
Rose, H.J.
Hutchinson's University Library , [date of publication not identified]
Buku Teks