1. Sedimentation of the Middle Precambrian Tyler Formation of northcentral Wisconsin and northwestern Michigan,;Alwin,1976
2. Geological Survey of Canada Paper;Annells,1973
3. Geological Survey of Canada Bulletin;Annells,1974
4. Paleobiology of a Precambrian shale;Barghoorn;Science,1965
5. U.S. Geological Survey Professional Paper;Books,1968