Kraemer, Richard H.
West Pub. Co, 1989
Buku Teks
Anderson, James E., author
Harper and Row, 1984
Buku Teks
Kraemer, H., author
D. A. Daamen's Uitgeversmaatschappij N.V., 1956
Buku Teks
Wheeler, Richard S.
Cornell University, 1970
Buku Teks
Johnson, Richard E., author
Houghton Mifflin , 1972
Buku Teks