S.Carter (N.E.Br.) 1987 - Carter S (1987) New Species and Taxonomic Changes amongst the Succulent Trees and Shrubs of Euphorbia subgen. Euphorbia from East Africa. Kew Bulletin 42(3): 673-682. doi: 10.2307/4110076.
There is no corrections for Euphorbia bussei var. kibwezensis yet.