Halleen, F., and G. Holz. “Cleistothecia and Flag Shoots: Sources of Primary Inoculum for Grape Powdery Mildew in the Western Cape Province, South Africa”. South African Journal of Enology and Viticulture, vol. 21, no. 2, May 2017, pp. 66-70, doi:10.21548/21-2-2212.