Model, Jan
ICG Publication, 1991
Buku Teks
Haeseryn, Walter Jan Maria
[publisher not identified], 1990
Buku Teks
W.G. Vagting
H.D.Tjeenk Willink and Zoon N.V,, 1951
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Pitlo, Adriaan
Gouda Quint BV, 1981
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Cortstens, G.J.M.
Gouda Quint BV., 1995
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