Bruyns (P.R.O.Bally) 2006 - Bruyns PV, Mapaya RJ, Hedderson T (2006) A New Subgeneric Classification for Euphorbia (Euphorbiaceae) in Southern Africa Based on ITS and psbA-trnH Sequence Data. Taxon 55(2): 397-420. doi: 10.2307/25065587.
There is no corrections for Euphorbia orobanchoides var. calycina yet.