A Tropical Rainforest in Colorado 1.4 Million Years After the Cretaceous-Tertiary BoundaryDOI: info:10.1126/science.1072102v. 296No. 55772379–2383
Johnson, Kirk R. 2002. "A Tropical Rainforest in Colorado 1.4 Million Years After the Cretaceous-Tertiary Boundary." Science, 296, (5577) 2379–2383. https://doi.org/10.1126/science.1072102.