Keeley, Jon E. Isoetes howellii: A Submerged Aquatic Cam Plant?. American Journal of Botany. 1981-03, 68 (3): 420. doi:10.2307/2442779.
Suissa, Jacob S; Green, Walton A. CO2 starvation experiments provide support for the carbon-limited hypothesis on the evolution of CAM-like behaviour in Isoëtes. Annals of Botany. 2021-01-01, 127 (1): 135–141. doi:10.1093/aob/mcaa153.
Keeley, Jon E. CAM photosynthesis in submerged aquatic plants. The Botanical Review. 1998-04, 64 (2): 121–175. doi:10.1007/BF02856581.
Keeley, Jon E.; Rundel, Philip W. Evolution of CAM and C 4 Carbon‐Concentrating Mechanisms. International Journal of Plant Sciences. 2003-05, 164 (S3): S55–S77. doi:10.1086/374192.