Interior world vol. 54
[publisher not identified], 2007
 Buku Referensi
Encyclopedia of psychology; Vol. 4
edited by Raymond J. Corsini
John Wiley & Sons, 1994
 Buku Referensi
Encyclopedia of mathematics Vol. 3
Kluwer Academic Publishers, 1995,
 Buku Referensi
Encyclopedia of mathematics Vol. 4
Kluwer Academic Publishers, 1995,
 Buku Referensi
Encyclopedia of mathematics Vol. 5
Kluwer Academic Publishers, 1995,
 Buku Referensi