Brostoff, Jonatham, author
Bloomsbury pubishing Limited, 1993
Buku Teks
Geddes & Grsset, 1997
Buku Teks
Douglas-Young, John, author
Parker Publishing Company, 1978
Buku Referensi
Church, James C., author
McGraw-Hill, 1979
Buku Referensi
Peters, Pamela, author
Wm.C. Brown Pub., 1993
Buku Referensi