1. R.D. Prengaman, Pb-80, Lead Development Association, London, 1980, p. 34.
2. Discontinuous and continuous hardening processes in calcium and calcium—tin micro-alloyed lead: influence of ‘secondary-lead’ impurities
3. Improved lead alloys for lead/acid positive grids in electric-vehicle applications
4. N.E. Bagshaw, in: T. Keily, B.W. Baxter (Eds.), Power Sources 12, Research and Development in Non-mechanical Electrical Power Sources, International Power Sources Symposium Committee, Leatherhead, England, 1989, p. 113.
5. P. Rao, U.S. Patent 5,298,350, 1994.