1. Systematic review of the genus Skolithos;Alpert;J. Paleontol.,1974
2. Trilobite and star-like trace fossils from the White-Inyo Mountains, California;Alpert;J. Paleontol.,1976
3. Organization, life, and systematics of trilobites;Bergström;Fossils Strata,1973
4. Lower Palaeozoic trace fossils from eastern Newfoundland;Bergström;Can. J. Earth Sci.,1976
5. Über den Buntsandstein in Deutschland und seine Bedeutung für die Trias;Bornemann;Beitr. Geol. Paläontol.,1889