By School Mathematics Project
By Parsonson, S. L.
By Nichols, Roger
By Weatherburn, C. E.
By Weston, J. D.
By Howson, A. G.
By Wenninger, Magnus J.
By Griffiths
By Matthews, Jean, White, Colin, Johnson, Howard, Gostling, Yvonne, Handbury, Michael, Hartman, Bob
By Riley, K. F., Hobson, M. P.
By Baker, Alan