Stark, W.
Kegan Paul, Trench, Trubner & Co, 1947
Buku Teks
Stark, W., author
Kegan Paul, Trenck, Trubner & Co., 1947
Buku Teks
Risjord, Norman K., author
Prentice-Hall, 1985
Buku Teks
Rand McNally and Company.
Rand Mcnally & Company, 2006
Buku Teks
Washington U.S. Department of Health, Education, and Welfare 1955
Buku Teks