Woll, Peter, author
Little, Brown, 1984
Buku Teks
Woll, Peter, author
Longman , 2001
Buku Teks
Woll, Peter, author
Little, Brown, 1965
Buku Teks
Herbert, Theodore T., author
Macmillan, 1976
Buku Teks
edited by Joseph Seibert & Gorden [i.e. Gordon] Wills
Penguin Books, 1970
Buku Referensi