APA Style

Pichi-Sermolli, R, E, G. (1965). Index filicum supplementum quartum pro annis 1934–1960 . Utrecht: International Bureau for Plant Taxonomy and Nomenclature.

MLA Style

Pichi-Sermolli, Rodolfo, Emilio, Giuseppe. "Index filicum supplementum quartum pro annis 1934–1960". Utrecht: International Bureau for Plant Taxonomy and Nomenclature, 1965. Digital.