Physical principles of pesticide behaviour: The Dynamics of Applied Pesticides in the Local Environment in Relation to Biological Response. G.S. Hartley and I.J. Graham-Bryce, Academic Press, London, 1980, Vol. 1, xxvi + 518 pp., £34.00 (U.K. only), U.S. $78.50, ISBN 0-12-328401-5; Vol. 2, xviii + 506 pp., £31.00 (U.K. only), U.S. $71.50, ISBN 0-12-328402-3