Pérez-Darniz, M., A. García-Méndez, and M. Medina. “Tillage Systems and Seeding Densities in Sweet Potato: Quality of Soil and Reserve Roots.”. Agronomy Mesoamerican, Vol. 28, no. 1, Dec. 2016, pp. 85-95, doi:10.15517/am.v28i1.22751.