Bekker, S.J., J.E. Hoffman, S.M. Jacobs, A.E. Strever, and J.L. Van Zyl. 2016. “Ecophysiology, Vigour, Berry and Wine Quality of Grapevines Growing on and off Heuweltjies”. South African Journal of Enology and Viticulture 37 (2):176-92. https://doi.org/10.21548/37-2-690.