Heijbroek, A.M.A.
Rabobank International Group, [Date of publication not identified]
Buku Teks
Jolley, Elizabeth
Fremantle Arts Centre Press, 1988
Buku Teks
Chen, James C. P.
Wiley, 1985
Buku Referensi
Marianne Wait, editor
Reader's Digest, 2007
Buku Teks
Bogaards, Carla
De Bezige Bij, 1990
Buku Teks