Harvey, Bill, author
Elsevier , 2005
Buku Teks
Bailey, Stephen K., author
Henry Holt, 1952
Buku Teks
Editor by Lawrence C.Dood; Bruce I. Oppenheimer
Congressional Quarterly Press, 1981
Buku Teks
National Library of Indonesia & Indonesian Library Association, 1991
Buku Referensi
Wilber, Ken, author
Shambhala, 1996
Buku Teks