Oligocene Age of the Classic Belen Fruit and Seed Assemblage of North Coastal Peru based on Diatom BiostratigraphyDOI: info:10.1086/665797v. 120No. 4University of Chicago Press467–476
Manchester, Steven R., Herrera, Fabiany, Fourtanier, Elisabeth, Barron, John, and Martinez, Jean-Noel. 2012. "Oligocene Age of the Classic Belen Fruit and Seed Assemblage of North Coastal Peru based on Diatom Biostratigraphy." Journal of Geology, 120, (4) 467–476. https://doi.org/10.1086/665797.