By D. W. G. Ballentyne, D. Lovett
By Knapp, B. J.
By School Mathematics Project
By Jennings, Terry
By B. J. Knapp
By Neil Short
By Wendy Madgwick
By Rick Turton
By Chris Oxlade
By P. Manning
By Robin Kerrod
By Peter D. Riley
By Dixon, Malcolm, Smith, Karen
By K Whyman
By S Aston
By Peter Riley
By Ian Rohr
By Mr Martin Kemp
By Knapp, Brian
By F.E. Close, Michael Marten, Christine Sutton
By Janice M. Morse
By Kuhn, Thomas S.
By Quinn, Emily
By Robin McKie