Riccardi, A. C., & Medina, F. A. The genus Ptychoceras d'Orbigny in the Aptian-Albian of Patagonia and Antarctica. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 249(1), 9.
Chicago Style (17th ed.) CitationRiccardi, Alberto Carlos, and Francisco Alberto Medina. "The Genus Ptychoceras D'Orbigny in the Aptian-Albian of Patagonia and Antarctica." Neues Jahrbuch Für Geologie Und Paläontologie - Abhandlungen 249, no. 1 (): 9.
MLA (9th ed.) CitationRiccardi, Alberto Carlos, and Francisco Alberto Medina. "The Genus Ptychoceras D'Orbigny in the Aptian-Albian of Patagonia and Antarctica." Neues Jahrbuch Für Geologie Und Paläontologie - Abhandlungen, vol. 249, no. 1, , p. 9.
Warning: These citations may not always be 100% accurate.