1. Leahy, E. P. and Karustis, G. A.U.S. patent 4,067,784, 1978.
2. Warwich, E. H.; Warwich, H. H.; Weisberg, A. M.U.S. patent 4,126,524, 1978.
3. Mirror-bright silver plating from a cyanide-free bath
4. Novev, T. V.; Ovcharov, S. D.; Yordanov, N. S.;et al.U.S. patent 4,279,708, 1981.