The SAGE Handbook of Biogeography. SAGE Publications, 2011-09-22, p. 143–. ISBN 978-1-4462-5445-5 [Consulta: 7 agost 2013]. «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 ...»
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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.