1. Distribution of the Middle Ordovician Copenhagen formation and its trilobites in Nevada Author/Creator: Ross, Reuben James, 1918- author Publication/Creation: Washington : United States Department of the Interior, Geological Survey, 1972 Format: Book Access & Availability: Loading
2. Distribution of the Middle Ordovician Copenhagen formation and its trilobites in Nevada, Author/Creator: Ross, Reuben James, 1918- Publication/Creation: Washington : U.S. Govt. Print. Off, 1972 Format: Book Is Part Of: U.S. Geological Survey professional paper, no. 744-749. Access & Availability: Loading