TY  - RPRT
TI  - Stratigraphy of Middle Ordovician rocks in the zinc-lead district of Wisconsin, Illinois, and Iowa
AU  - A.F. Agnew
AU  - A. V. Heyl
AU  - C. H. Behre
AU  - E.J. Lyons
PY  - 1956
DO  - 10.3133/pp274k
UR  - https://pubs.usgs.gov/publication/pp274K
ID  - pp274K
ER  -