Verbatim text: Duncan, R. E. 1940. The cytology of sporangium development in Azolla filiculoides. Bull. Torrey Bot. Club 67: 391--412.
Author: Duncan, R.E.
Year: 1940
Title: The cytology of sporangium development in Azolla filiculoides
Journal: Bull. Torrey Bot. Club
Volume: 67
Pages: 391–412