^ abAngiosperm Phylogeny Group (2009), "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III", Botanical Journal of the Linnean Society, 161 (2): 105–121, doi:10.1111/j.1095-8339.2009.00996.x, hdl:10654/18083
^Andrew Millington; Mark Blumler; Udo Schickhoff (2011-09-22). The SAGE Handbook of Biogeography. SAGE Publications. pp. 143–. ISBN978-1-4462-5445-5. Retrieved 2013-08-07. The Cape Floristic Region in South Africa is comparatively rich in endemic flowering-plant families. Five families of angiosperms (Penaeaceae, Roridulaceae, Geissolomataceae, Grubbiaceae, and Lanariaceae) are endemic to that region ...
^Stevens, P. F. (2001 onwards). Penaeaceae.. Angiosperm Phylogeny Website. Version 12, July 2012 [and more or less continuously updated since]. Accessed online: 5 June 2013.