By B.D. Bunday, H. Mulholland
By Malcolm Pemberton
By CGP Books
By Prof. Alan Smith, Sophie Goldie
By M. Garcia-Sancho
By Ric Pimentel, Terry Wall
By Raymond Barnett, Michael Ziegler, Karl Byleen, David Sobecki
By Sheine Peart
By G. Lewis
By M. Foote
By Fauvel, John, Gray, Jeremy, John Fauvel, Jeremy Gray
By Karl Soreskos
By Marion Cranmer, Catherine Musto, Catherine Mutso
By Wenham, Martin W
By School Mathematics Project
By D.C. Perkins, E.J. Perkins
By David Alan Herzog
By J.L. Smyrl
By Beare
By Patricia C. Kenschaft
By June Lowenstein
By Mary Jane Sterling
By Learning by Questions Team
By Mary Jane Sterling (Bradley University, Peoria, IL)
By Peter H. Selby, Steve Slavin
By L. B. Resnick, W. W. Ford
By R. Davison, L. Cochrane
By Scottish Primary Maths Group SPMG