Canan, E. D. (1946). A key to the ferns of Pennsylvania: Includes a non-technical key for investigation of each of the fifty-nine species found in the state; directions for use of the key; an outline for aid in identification of ferns by sterile fronds alone; distribution of species through the state; and a list of ferns found in the vicinity of Johnstown, Cambria County. [Lancaster, Pa.: Science Press].

Canan, Elsie Deane. A Key to the Ferns of Pennsylvania: Includes a Non-technical Key for Investigation of Each of the Fifty-nine Species Found in the State; Directions for Use of the Key; an Outline for Aid in Identification of Ferns By Sterile Fronds Alone; Distribution of Species Through the State; and a List of Ferns Found in the Vicinity of Johnstown, Cambria County. [Lancaster, Pa.: Science Press], 1946.

Canan, Elsie Deane. A Key to the Ferns of Pennsylvania: Includes a Non-technical Key for Investigation of Each of the Fifty-nine Species Found in the State; Directions for Use of the Key; an Outline for Aid in Identification of Ferns By Sterile Fronds Alone; Distribution of Species Through the State; and a List of Ferns Found in the Vicinity of Johnstown, Cambria County. [Lancaster, Pa.: Science Press], 1946.