Odum, Howard W.
Longmans Green, 1951
Buku Teks
Mott, Frank Luther
Macmillan, 1956
Buku Teks
edited by Hans L. Zetterberg
Unesco, 1956
Buku Teks
Mott, Frank Luther
New York The MacMillan Company 1947
Buku Teks
Link, Arthur S.
Alfreda A. Knopf, 1955
Buku Teks