RT Journal Article SR Electronic T1 A new model for atmospheric oxygen over Phanerozoic time JF American Journal of Science JO Am J Sci FD American Journal of Science SP 333 OP 361 DO 10.2475/ajs.289.4.333 VO 289 IS 4 A1 Berner, Robert A. A1 Canfield, Donald E. YR 1989 UL http://www.ajsonline.org/content/289/4/333.abstract AB