Field, W. D., & Herrera, J. (1977). The pierid butterflies of the genera Hypsochila Ureta, Phulia Herrich-Schäffer, Infraphulia Field, Pierphulia Field, and Piercolias Staudinger. Smithsonian Institution Press.
Chicago Style (17th ed.) CitationField, William Dewitt, and José Herrera. The Pierid Butterflies of the Genera Hypsochila Ureta, Phulia Herrich-Schäffer, Infraphulia Field, Pierphulia Field, and Piercolias Staudinger. Washington, D.C.: Smithsonian Institution Press, 1977.
MLA (9th ed.) CitationField, William Dewitt, and José Herrera. The Pierid Butterflies of the Genera Hypsochila Ureta, Phulia Herrich-Schäffer, Infraphulia Field, Pierphulia Field, and Piercolias Staudinger. Smithsonian Institution Press, 1977.
Warning: These citations may not always be 100% accurate.