By Russell F Jacobs
By Muschla, Judith A., Gary Robert
By Hale, Melissa Warner
By Mills, Steve, Koll, Hilary
By School Mathematics Project
By The 11+ Company, Richard E. Martin
By Green, Dan, Basher, Simon
By Pratt, Kathy, Kirby, Elizabeth
By Heylings, M. R.
By Brodie, Andrew
By Merttens BA MED, Ruth
By Owen, Annie
By Vorderman, Carol
By Oliver, Diane
By Pate, Katherine
By Kirkby, Dave, Dave Kirkby
By Abbott, Paul, Wardle, Michael
By Hirst, Keith
By Hunter, John, Scottish Mathematics Group, Monk, David
By Poskitt, Kjartan, Reeve, Philip
By John Mason, Alan Graham, Sue Johnston-Wilder
By Nicholson, Su
By Various
By Books, CGP
By Webber, B., Barnes, T.
By Dickinson, Paul, Hough, Susan, Eade, Frank, Gough, Steve, Dudzic, Stella
By Michael Cornelius