Gissel, S. Tools and Tillage. A Journal on the History of the Implements of Cultivation and Other Agricultural Processes. Edited by Axel Steensberg, Alexander Fenton and Grith Lerche. Copenhagen, G. E. C. Gad. Vol. 1:1.1968. 64 Ss. Hl. Subskription 3 $. ht 1970, 12.