Paleocene fresh-water mollusks from Southern Montana Yen, Teng-Chien creator author. Geological Survey (U.S.) issuing body. text bibliography dcu 1947 monographic eng remote 1 online resource (20 unnumbered pages) : illustrations. by Teng-Chien Yen. Title from title screen (viewed September 22, 2014). Includes bibliographical references and index. n-us-mt Mollusks, Fossil Montana Paleontology Paleocene Cretaceous Geologic Period Gastropoda, Fossil Mollusks Paleontology Montana From 65 to 140 million years ago fast I 19.16:214-C I 19.16:214-C Paleocene fresh-water mollusks from Southern Montana Yen, Teng-Chien. (OCoLC)6070631 Professional paper (Geological Survey (U.S.)) ; no. 214-C Shorter contributions to general geology ; 1947 https://purl.fdlp.gov/GPO/gpo80541 COP 140929 20211120182251.0 in00003838913 eng