Taylor, David Winship; Li, Hongqi; Dahl, Jeremy; Fago, Fred J.; Zinniker, David; Moldowan, J. Michael (March 2006). "Biogeochemical evidence for the presence of the angiosperm molecular fossil oleanane in Paleozoic and Mesozoic non-angiospermous fossils". Paleobiology. 32 (2): 179–90. doi:10.1666/0094-8373(2006)32[179:BEFTPO]2.0.CO;2. S2CID83801635.
Taylor, David Winship; Li, Hongqi; Dahl, Jeremy; Fago, Fred J.; Zinniker, David; Moldowan, J. Michael (March 2006). "Biogeochemical evidence for the presence of the angiosperm molecular fossil oleanane in Paleozoic and Mesozoic non-angiospermous fossils". Paleobiology. 32 (2): 179–90. doi:10.1666/0094-8373(2006)32[179:BEFTPO]2.0.CO;2. S2CID83801635.