Geology of the country around Braintree : memoir for 1,50 000 geological sheet 223 (England and Wales) / R.A. Ellison and R.D. Lake ; contributors, stratigraphy, C.R. Bristow ; economic geology, P.M. Hopson ; petrology, R.J. Merriman. - Ellison, R. A. (H.M.S.O., 1986)