References for Azollaceae
Brunton, D.F. 1986. Status of the mosquito fern, Azolla mexicana Salviniaceae, in Canada. Can. Field-Nat. 100:404-408.
Svenson, H.K. 1944. The new world species of Azolla. Amer. Fern J. 34:69-84.

Source for the Reference Lists

George W. Douglas, Del Meidinger and Jim Pojar. 1998-2002. Illustrated Flora of British Columbia.