TY  - RPRT
TI  - Reports and maps of the Geological Survey released only in the open files, 1957
AU  - Betsy Anne Weld
AU  - Erwin S. Asselstine
AU  - Arthur Johnson
PY  - 1958
DO  - 10.3133/cir403
UR  - https://pubs.usgs.gov/publication/cir403
ID  - cir403
ER  -