Goodrich, Leland M.
Thomas Y. Crowell, 1961
Buku Teks SO
Coyle, David Cushman, 1887-1969
Columbia University Press, 1963
Buku Teks SO
edited by James Barros
Free Press, 1972
Buku Teks SO
by United Nations
Departemen of Public Information UN, 1989
Buku Teks SO
by Department of Public Information United Nations
United Nations Department of Public Information, 1989
Buku Teks SO