By Heinz-Otto Peitgen, etc., H. Jurgens, D. Saupe (all of the University of Bremen, Germany)
By Richard Gillings
By School Mathematics Project
By Nuffield Foundation
By Smith, P.
By Wendy Clemson
By Margaret L. Lial, Charles D. Miller
By David Rayner
By E. Graham
By Daniel B. Wright, Kamala London
By Serena Alexander, David Hillard
By Ginn, Merttens, Ruth, Kirkby, David
By Paul Dickinson, Susan Hough, Frank Eade, Steve Gough, Stella Dudzic
By E.K.Victor Pearce
By Angela Wilkes
By B.K. Holdsworth
By Scottish Primary Maths Group SPMG
By Daniel Tammet
By Peter Connah
By Oliver Penrose, Peter Taylor
By John Davidson
By J. Borowski, Jonathan M. Borwein
By Ennos, Roland
By H. Nicholson, et al
By CGP Books
By Jiri Louda, Michael Maclagan