By O'Neill, Robert, etc., Kingsbury, R, Yeadon, T, Scott
By Betty Morgan Bowen, Roger H Flavell, Monica Vincent
By Scottish Primary Mathematics Group
By Vorderman, Carol, Hudson, Miles
By Reynoldson, Fiona
By Abrahams, Peter
By Abbott, A.F., Nelkon, Michael
By Dickens, Charles
By SPMG
By Umeasiegbu, Remo Nna
By Salters' Science Team, Aitkin, Mary, etc.
By N.G. Masson, F. Monaghan, L. Thompson
By Whitcomb, Alan
By Smethers, Michael
By Hall, A.G.
By Harrison, John
By Wyss, Johann, Swan, D.K., West, Michael