Plazinski, J., Zheng, Q., Taylor, R., Croft, L., Rolfe, B. G., & Gunning, B. E. S. (1990). DNA Probes Show Genetic Variation in Cyanobacterial Symbionts of the Azolla Fern and a Closer Relationship to Free-Living Nostoc Strains than to Free-Living Anabaena Strains.

Plazinski, Jacek, Qi Zheng, Rona Taylor, Lynn Croft, Barry G. Rolfe, and Brian E. S. Gunning. DNA Probes Show Genetic Variation in Cyanobacterial Symbionts of the Azolla Fern and a Closer Relationship to Free-Living Nostoc Strains Than to Free-Living Anabaena Strains. 1990.

Plazinski, Jacek, et al. DNA Probes Show Genetic Variation in Cyanobacterial Symbionts of the Azolla Fern and a Closer Relationship to Free-Living Nostoc Strains Than to Free-Living Anabaena Strains. 1990.