Steyn, H. M., & Wyk, A. E. V. (2017).

Taxonomic notes on Acanthopsis Harv. (Acanthaceae, tribe Acantheae): the group with trifid bracts

. Phytotaxa, 295(3), 201–217. https://doi.org/10.11646/phytotaxa.295.3.1