Lundy, James L., author
Eurasia Publishing House, 1968
Buku Teks
Roy, Robert H., author
John Hopkins Press, 1958
Buku Teks
Spriegel, William Robert, 1893-1972, author
Charles & Tuttle, 1958
Buku Teks
Seckler-Hudson, Catheryn, author
Washington, D.C., The American University Press
Buku Teks
Heyel, Carl, author
American Management Association, 1960
Buku Teks