"Species affinis (Affinis)". Dictionary of botanic terminology. cactus-art.biz. Retrieved 13 December 2010. http://www.cactus-art.biz/note-book/Dictionary/Dictionary_S/dictionary_species_affinis.htm
Oxford Latin Dictionary. Oxford University Press. 1968. p. 79.
Bengtson, Peter (1988). "Open Nomenclature". Palaeontology. 31 (1): 223–227. Archived (PDF) from the original on 6 October 2014. https://www.palass.org/publications/palaeontology-journal/archive/31/1/article_pp223-227
Sigovini, Marco; Keppel, Erica; Tagliapietra, Davide (2016). "Open Nomenclature in the biodiversity era". Methods in Ecology and Evolution. 7 (10): 1217–1225. doi:10.1111/2041-210X.12594. https://doi.org/10.1111%2F2041-210X.12594
Bengtson, Peter (1988). "Open Nomenclature". Palaeontology. 31 (1): 223–227. Archived (PDF) from the original on 6 October 2014. https://www.palass.org/publications/palaeontology-journal/archive/31/1/article_pp223-227