Runge, Laura L., author
Cambridge University Press, 1997
eBooks
Tindall, William York, author
Books for Libraries Press, 1947
Buku Teks
Davis, Con, author
Longman, 1991
Buku Teks
editor, Stuart Sim
Prentice-Hall, 1995
Buku Referensi
Compiled and edited by Dorothy Nyren Curley, Maurice Kramer, Elaine Fialka Kramer
Continuum, 1989
Buku Referensi