Ellipsocephalid trilobites from Cambrian Series 2 and Stage 4, with emphasis on the taxonomy, morphological plasticity and biostratigraphic significance of ellipsocephalids from Scania, Sweden Geyer, Gerd Cederström, Peter Nilsson, Carin H. Ahlberg, Per Ahlgren, John 9788215065762 Fossils and strata 67 Heftet 05.09.2022 Engelsk I salg
Major Events in Early Vertebrate Evolution Ahlberg, Per Erik 9780415233705 Systematics Association Special Volumes Innbundet 15.02.2001 Engelsk I salg
