Gowan, S. P. (1991). Systematics of North American species of Porpidia (lichenized ascomycotina), with reference to other members of the Porpidiaceae (Reprint d. Ausg. von 1988.). University Microfilms International.
Chicago-Zitierstil (17. Ausg.)Gowan, Sharon Phyllis. Systematics of North American Species of Porpidia (lichenized Ascomycotina), with Reference to Other Members of the Porpidiaceae. Reprint d. Ausg. von 1988. Ann Arbor, Mich: University Microfilms International, 1991.
MLA-Zitierstil (9. Ausg.)Gowan, Sharon Phyllis. Systematics of North American Species of Porpidia (lichenized Ascomycotina), with Reference to Other Members of the Porpidiaceae. Reprint d. Ausg. von 1988. University Microfilms International, 1991.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.