Oil and Gas in the Adams-Brown-Schuyler County Area, Illinois (Classic Reprint) Howard, Richard Henry Heftet / 2018 / Engelsk
Wapella East Oil Pool, Dewitt County, Illinois: A Silurian Reef (Classic Reprint) Howard, Richard Henry Heftet / 2019 / Engelsk
Niagaran Reefs and Oil Accumulation in the Dewitt-McLean County Area, Illinois (Classic Reprint) Howard, Richard Henry Heftet / 2019 / Engelsk
Oil and Gas in the Adams-Brown-Schuyler County Area, Illinois (Classic Reprint) Howard, Richard Henry Innbundet / 2018 / Engelsk
Niagaran Reefs and Oil Accumulation in the Dewitt-McLean County Area, Illinois (Classic Reprint) Howard, Richard Henry Innbundet / 2019 / Engelsk
Wapella East Oil Pool, Dewitt County, Illinois: A Silurian Reef (Classic Reprint) Howard, Richard Henry Innbundet / 2019 / Engelsk