The ammonites of the Middle Jurassic Cranocephalites beds of East Greenland
· John H Callomon, Peter Alsen & Finn Surlyk ; with an appendix by Peter Alsen : description of a new Bajocian (Middle Jurassic) ammonite species, Cranocephalites tvaerdalensis sp.nov., from Geographical Societ Ø, North-East Greenland
Bok Engelsk 2015