Gibbs, Peter
J.B. Lippincott Company, 1963
Buku Teks
Ruaidah, author
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 2002
UI - Skripsi (Membership)
Lord, Walter, author
Harper & Row, Publisher, 1967
Buku Teks
McPherson, James M.
Oxford University Press, 2002
Buku Teks
Sears, Stephen W., author
Houghton Miffiln, 2003
Buku Teks