Paudyal, S., R. R. Aryal, S. Chauhan, and D. Maheshwari. “Effect of Heavy Metals on Growth of Rhizobium Strains and Symbiotic Efficiency of Two Species of Tropical Legumes”. Scientific World, vol. 5, no. 5, Feb. 2010, pp. 27-32, doi:10.3126/sw.v5i5.2652.