1. M. K. Das (1979) Machines and Tooling for Cropping, BCFG Seminar on Slug and Billet Preparation for Forging, Birmingham, 11 th April.
2. M.H.M. Ahmed and M. K. Das (1978) An Experimental Study of the Double Cropping Process, 19th Int, M.T.D.R. Conf., Manchester.
3. G.V. Marston (1963) Shearing of Bar and Billet Forging Stock, Metal Treatment and Drop Forging, No. 11.
4. J. Everett (1976) Fully Automated Feeding Equipment for the High-Speed Precision Cropping of Bar Stock, Metallurgic and Metal Forming, No. 2.
5. Anon. (1978) Precision Crop Units, Trade Literature, Cold Extrusion Equipment Co., Surrey, England.