Revisions of stratigraphic nomenclature within the Keweenawan supergroup of northern Michigan / by William F. Cannon and Suzanne W. Nicholson. Geochemistry, petrography, and volcanology of rhyolites of the Portage Lake Volcanics, Keweenaw Peninsula, Michigan / by Suzanne W. Nicholson
(Contributions to the geology and mineral resources of the midcontinent rift system ; ch. A-B) (U.S. Geological Survey bulletin ; 1970-A,B)