Klein, M., author
Groningen Wolters-Noordhoff 1985
Buku Teks
Middel, Anita
Boekwerk, 1992
Buku Teks
Geddes & Grosset, 2003
Buku Referensi
editor, Bud Wileman, Robin Wileman, Bessana C. Sewell
Wileman Publications, 1986
Buku Referensi
Carney, Edward
Routledge,, 1997
Buku Teks