Kokubugata, G., Nakamura, K., Hirayama, Y., & Yokota, M. (2013).

Taxonomic reexamination of Portulaca okinawensis (Portulacaceae) in
the Ryukyu Archipelago of Japan based on molecular and morphological data

. Phytotaxa, 117(1), 11–20. https://doi.org/10.11646/phytotaxa.117.1.2