Harkins, William E., author
Littlefield, Adams, 1959
Buku Referensi
by H. van Gorp ... [and others]
Wolters-Noordhoff, 1991
Buku Teks
Zalm, Cees Van Der, author
Het Spectrum, 1990
Buku Referensi
edited by Margaret Drabble
Oxford University Press, 1985
Buku Referensi
Wilde, William H., author
Oxford University Press, 1994
Buku Referensi