OCCURRENCE OF BIOGENIC STERANES AND PENTACYCLIC TRITERPANES IN AN EOCENE SHALE (52 MILLION YEARS) AND IN AN EARLY PRECAMBRIAN SHALE (2.7 BILLION YEARS): A PRELIMINARY REPORT.
Burlingame
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DEPARTMENT OF CHEMISTRY, UNIVERSITY OF CALIFORNIA, BERKELEY.
Haug
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Belsky
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Calvin
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