Susila, Eka, et al. “Population and Diversity of Indigenous Arbuscular Mycorrhizal Fungi from Shallots Rhizosphere in Different Altitudes in West Sumatra”. International Journal on Advanced Science, Engineering and Information Technology, vol. 7, no. 5, Oct. 2017, pp. 1886-93, doi:10.18517/ijaseit.7.5.1592.