Pitlo, Adriaan, author
Gouda Quint BV, 1981
Buku Teks
Cortstens, G.J.M.
Gouda Quint BV., 1995
Buku Teks
Heynderickx, Priscilla, author
Lessius Hogeschool, 2001
Buku Teks
Wester, J.
de haan, 1989
Buku Teks
Heestermans, Hans, author
Thomas Rap, [Date of publication not identified]
Buku Referensi