Evizal, R., . Tohari, I. D. Prijambada, J. Widada, and D. Widianto. “Soil Bacterial Diversity and Productivity of Coffee - Shade Tree Agro-Ecosystems”. JOURNAL OF TROPICAL SOILS, vol. 17, no. 2, Nov. 2012, pp. 181-7, doi:10.5400/jts.2012.v17i2.181-187.