1. US Environmental Protection Agency, Strategy for Reducing Lead Exposure, 21 February, 1991.
2. US Environmental Protection Agency, Advanced Notice of Rulemaking, 13 May, 1991.
3. US Environmental Protection Agency, Comprehensive Review of Lead in the Environmental under TSCA, 56 FR 22096-98, 13 May, 1991.
4. Lead-free solder Materials, COST Action 531, http://www.univie.ac.at/cost5531/.
5. Bismuth activity in lead-free solder Bi–In–Sn alloys