Olson, Everett C. (1982). "Extinctions of Permian and Triassic nonmarine vertebrates". Geological Implications of Impacts of Large Asteroids and Comets on the Earth. Geological Society of America Special Papers. Vol. 190. pp. 501–512. doi:10.1130/SPE190-p501. ISBN0-8137-2190-3. ISSN0072-1077.
Modesto, Sean P.; Smith, Roger M. H.; Campione, Nicolás E.; Reisz, Robert R. (December 2011). "The last "pelycosaur": a varanopid synapsid from the Pristerognathus Assemblage Zone, Middle Permian of South Africa". Naturwissenschaften. 98 (12): 1027–1034. Bibcode:2011NW.....98.1027M. doi:10.1007/s00114-011-0856-2. PMID22009069. S2CID27865550.
Modesto, Sean P.; Smith, Roger M. H.; Campione, Nicolás E.; Reisz, Robert R. (December 2011). "The last "pelycosaur": a varanopid synapsid from the Pristerognathus Assemblage Zone, Middle Permian of South Africa". Naturwissenschaften. 98 (12): 1027–1034. Bibcode:2011NW.....98.1027M. doi:10.1007/s00114-011-0856-2. PMID22009069. S2CID27865550.
Modesto, Sean P.; Smith, Roger M. H.; Campione, Nicolás E.; Reisz, Robert R. (December 2011). "The last "pelycosaur": a varanopid synapsid from the Pristerognathus Assemblage Zone, Middle Permian of South Africa". Naturwissenschaften. 98 (12): 1027–1034. Bibcode:2011NW.....98.1027M. doi:10.1007/s00114-011-0856-2. PMID22009069. S2CID27865550.
Modesto, Sean P.; Smith, Roger M. H.; Campione, Nicolás E.; Reisz, Robert R. (December 2011). "The last "pelycosaur": a varanopid synapsid from the Pristerognathus Assemblage Zone, Middle Permian of South Africa". Naturwissenschaften. 98 (12): 1027–1034. Bibcode:2011NW.....98.1027M. doi:10.1007/s00114-011-0856-2. PMID22009069. S2CID27865550.
Olson, Everett C. (1982). "Extinctions of Permian and Triassic nonmarine vertebrates". Geological Implications of Impacts of Large Asteroids and Comets on the Earth. Geological Society of America Special Papers. Vol. 190. pp. 501–512. doi:10.1130/SPE190-p501. ISBN0-8137-2190-3. ISSN0072-1077.