Leuenberger, B. E.: Opuntia paraguayensis (Cactaceae) reassessed. — Willdenowia 31: 181–187. 2001. — ISSN 0511-9618.
The confusing history of the name Opuntia paraguayensis is described. A closer examination of the protologue as compared to the use of the name in literature revealed that it has been misapplied to O. elata and O. cardiosperma. The type specimen of O. paraguayensis was presumably destroyed in Berlin, in 1943. Another specimen under this name in the spirit collection at Berlin-Dahlem, collected by Hassler, is undoubtedly O. ficus-indica. It is designated as the neotype of O. paraguayensis.