Reid, Jill D.; Plunkett, Gregory M.; Peters, Gerald A. (May 2006). "Phylogenetic Relationships in the Heterosporous Fern Genus Azolla (Azollaceae) Based on DNA Sequence Data from Three Noncoding Regions". International Journal of Plant Sciences. 167 (3): 529–538. doi:10.1086/501071. ISSN1058-5893.
Reid, Jill D.; Plunkett, Gregory M.; Peters, Gerald A. (May 2006). "Phylogenetic Relationships in the Heterosporous Fern Genus Azolla (Azollaceae) Based on DNA Sequence Data from Three Noncoding Regions". International Journal of Plant Sciences. 167 (3): 529–538. doi:10.1086/501071. ISSN1058-5893.