1. “Die galvanische Vergoldung und Versilberung,”;ELSNER,1851
2. F. VOLK, Electrolytic deposition of gold and gold alloys. U. S. Patent 2,812,299 (1957).
3. also German Patent 801,312 (1951).
4. E. C. RINKER and R. DUVA, Electroplating bright gold. U. S. Patent 2,905,601 (1959).
5. Acid gold plating;EHRHARDT;Proc. Am. Electroplaters' Soc.,1960