Seckler-Hudson, Catheryn, author
Washington, D.C., The American University Press
Buku Teks
written by M. C. Barnes [and others]
Allen & Unwin, 1970
Buku Teks
Woodward, Joan, author
Oxford University Press, 1965
Buku Teks
Lawrence L. Bethel ... [et al.]
McGraw-Hill, 1945
Buku Teks
by James L. Riggs ... [et al.]
McGraw-Hill, 1979
Buku Teks