Goodrich, Leland M.
Thomas Y. Crowell, 1961
Buku Teks
Walker, Edward Everett, 1900-1974
Charles Scribner's Sons, 1943
Buku Teks
by United Nations
Departement of Public Information - United Nations, 1956
Buku Teks
Whittaker, David J.
Routledge, 1997
Buku Teks
Coyle, David Cushman, 1887-1969
The New Americanan Library, 1962
Buku Teks