Using mathematical thinking (Course Units for The Open University Second Level Course ME234). Pp 20, 56,40, 72,44,48, 64,48,48,48, 32,40, 32. £35 (full set only). 1989. ISBN 0-335-14345-8, 14346-6, 14347-4, 14348-2, 14349-0, 14350-4, 14351-2, 14352-0, 14353-9, 14354-7, 14355-5, 14356-3, 14357-1 (Open University Educational Enterprises Ltd)