Challen, D.W
Longman Cheshire, 1979
Buku Teks
Library of Congress, Cataloging Distribution Service, 1997
Buku Referensi
Adcock, Sir Frank
Thames and Hudson, 1975
Buku Teks
Harper, 1961
Buku Teks
Hoyer, Wayne D., author
South Western Cengage Learning, 2012
Buku Teks