Robert M. Hutchins, Mortimer J. Adler, editors in chief
Encyclopaedia Britannica, Inc., 1963
Buku Referensi
Campbell, Oscar James, author
Crofts, 1947
Buku Teks
edited by Josephine K. Piercy
Macmillan, 1930
Buku Teks
Narogin, Mudrooroo, author
Hyland House, 1990
Buku Teks
edited by. Richard Garnett
Delhi, India Akashdeep 1992
Buku Referensi