By School Mathematics Project
By Neill, Hugh, Quadling, Douglas
By Montague-Smith, Ann, Harrison, Paul
By Harrison, Paul, Montague-Smith, Ann, Paul Harrison, Ann Montague-Smith
By Harrison, Paul, Montague-Smith, Ann
By Crowden, Jane, Cowling, Sandy, King, Andrew, Mumford, Jeanette
By Cowling, Sandy, Crowden, Jane, King, Andrew, Mumford, Jeanette
By BBC
By Turner, D. A., etc., Hony, B.V., Ledsham, A., Oakley, K.D., Potts, I.A., Lane, P.S.
By Hony, Viv, Turner, David, Oakley, K, Lane, P
By Shuard, H
By Eric A. Albany
By NCCT
By Paul Latham, Percy Truelove
By Fleet, Tony
By Speed, Brian