Okoronkwo, N., & Van Hove, C. (1987). Dynamics of Azolla-anabaena Nitrogenase Activity in the Presence and Absence of Combined Nitrogen. Microbios : a prestige international biomedical research journal of chemical and general microbiology, 49(198), 39-45. https://hdl.handle.net/2078.5/42741 (Original work published 1987)