Lyon, Peter
Buku Teks
Kranz, Rachel, author
Factsts On File, Inc, 2005
Buku Teks
Buku Teks
Hartman, Philip E.
Prentice Hall of India Private Limited, 1972
Buku Referensi
Learned, Edmund P. (Edmund Philip), 1900-1991, author
Harvard University Press, 1951
Buku Teks