Supplement to: Gulbrandsen, R A; Reeser, D W (1969): An occurrence of Permian manganese nodules near Dillon, Montana. In: Geological Survey Research 1969, Chapter C, U.S. Geological Survey Professional Paper; http://pubs.usgs.gov/pp/0650c/report.pdf, 650C, 49-57, hdl:10013/epic.46181.d003