By Lesley Snowball, Kenneth Snowball
By Catterall, Peter
By Seely, John
By Seely, John, etc., Barlow, Steve, Skidmore
By Miller, Arthur
By Hapgood, Michael
By RSA Examinations Board
By Jones, Carol Barton
By Howker, Janni
By Karavis, Sylvia, Matthews, Gill
By Scottish Primary Mathematics Group
By Bromhead, Peter
By Crichton, Michael
By Barratt, Margaret
By Centre for Innovation in Mathematics Teaching - University of Exeter
By Avery, J.H., Nelkon, Michael
By Sawers, Robin
By O'Neill, Robert, etc., Kingsbury, R, Yeadon, T, Scott