Wells, Ronald A.
Mouton, 1973
Buku Teks
Landau, Sidney I., author
Cambridge University Press, 2001
Buku Referensi
edited by Raven I. Mcdavid and Audrey R. Duckert
Foresman and Company,
Buku Teks
Buku Teks
Henning Bergenholtz, editor
Peter Lang, 2009
Buku Teks