Klak (L.Bolus) 2007 - Klak C, Bruyns PV, Hedderson TAJ (2007) A Phylogeny and New Classification for Mesembryanthemoideae (Aizoaceae). Taxon 56(3): 737-756. doi: 10.2307/25065858.
There is no corrections for Mesembryanthemum digitatum subsp. littlewoodii yet.