W. van Averbeke, T. Tshikalange, and K. Juma, “The commodity systems of <i>Brassica rapa</i> L. subsp. chinensis and <i>Solanum retroflexum</i> Dun. in Vhembe, Limpopo Province, South Africa”, WSA, vol. 33, no. 3, pp. 349–354, Dec. 2018.