TY  - RPRT
TI  - Controls on porphyrin concentrations of Pennsylvanian organic-rich shales, Western U.S.A.
AU  - J.L. Clayton
AU  - G.E. Michael
PY  - 2002
DO  - 10.1021/ef00024a004
UR  - https://pubs.usgs.gov/publication/70015877
ID  - 70015877
ER  -