Menezes, Dinah Mochel de, et al. “Harvesting Time in Relation to Sugar and Protein Content in Six Varieties of Sweet Potato”. Pesquisa Agropecuaria Brasileira, vol. 11, no. 12, Apr. 2014, pp. 49-52, doi:10.1590/S1678-3921.pab1976.v11.16921.