Spriegel, William Robert, 1893-1972, author
Charles & Tuttle, 1958
Buku Teks
Seckler-Hudson, Catheryn, author
Washington, D.C., The American University Press
Buku Teks
Lawrence L. Bethel ... [et al.]
McGraw-Hill, 1954
Buku Teks
Voich, Dan, author
Ronald Press, 1968
Buku Teks
Williamson, Oliver E., author
Prentice-Hall, 1970
Buku Teks