Ludvigsen, R. (1982). Upper Cambrian and Lower Ordovician trilobite biostratigraphy of the Rabbitkettle Formation, western District of Mackenzie. Royal Ontario Museum.
Čikaški stil citiranja (17. izdanje)Ludvigsen, Rolf. Upper Cambrian and Lower Ordovician Trilobite Biostratigraphy of the Rabbitkettle Formation, Western District of Mackenzie. Toronto, Canada: Royal Ontario Museum, 1982.
MLA način citiranja (9. izdanje)Ludvigsen, Rolf. Upper Cambrian and Lower Ordovician Trilobite Biostratigraphy of the Rabbitkettle Formation, Western District of Mackenzie. Royal Ontario Museum, 1982.
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