Reconstruction and interpretation of Brittsia problematica D. White (Fern, Pennsylvanian) / Hermann W. Pfefferkorn --.

v.33:no.17(1976)

Ferns and fern allies of Guatemala. Robert G. Stolze.

n.s. no.12(1983)

The British fern gazette.

v.1 (1909-1912)

The British fern gazette.

v.2 (1912-1915)