Robinson, O. Preston
Prentice Hall Inc., 1959
Buku Teks
Le Breton, Preston P.
Prentice-Hall, 1961
Buku Teks
Klass, David
Scholastic Inc., 1996
Buku Teks
Chinal, J.
Akademie-Verlag, 1973
Buku Teks
Le Breton, Preston P.
Englewood Cliffs, 1961
Buku Teks