Volume 12, Issue 6 (June 1, 2000)
By Shotaro Akaho, Hilbert J. Kappen
Volume 14, Issue 12 (December 1, 2002)
By Lovorka Pantic, Joaquín J. Torres, Hilbert J. Kappen, Stan C.A.M. Gielen
Volume 19, Issue 7 (July 2007)
By Daniele Marinazzo, Hilbert J. Kappen, Stan C. A. M. Gielen