Robuta

https://scholarworks.iu.edu/dspace/items/82a546f8-d25a-4f5a-84fc-9ed87f45d17e/full Arenaceous Foraminiferida and Zonation of the Silurian Rocks of Northern Indiana of the zonation silurian rocks northern https://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=GEODEBRGM6909029679 AN ANALYSIS OF THE SILURIAN KEEFER SANDSTONE OF PENNSYLVANIA. an analysis of the silurian keefer sandstone