AnasI., YulliawatiT. and HeinzemannJ. (2001) “Double Inoculation of Rhizobium and Arbuscular Mycorrhyzal fungus to Improve The Growth of Yam Bean”, Jurnal Ilmu Tanah dan Lingkungan, 2(2), pp. 18-22. doi: 10.29244/jitl.2.2.18-22.