Canudo, J.I., G. Keller, and E. Molina. (1991) 1991. “Cretaceous/Tertiary/Boundary/Extinction/Pattern/and/Faunal/Turnover/at/Agost/and/Caravaca,/S.E./Spain”. Marine Micropaleontology 17: 319–341. doi:10.1016/0377-8398(91)90019-3.

Keller, G., S.L. D’Hondt, C.J. Orth, J.S. Gilmore, P.Q. Oliver, E.M. Shoemaker, and E. Molina. (1987) 1987. “Late Eocene Impact Microspherules: Stratigraphy, Age and Geochemistry”. Meteoritics 22: 25–60. doi:10.1111/j.1945-5100.1987.tb00883.x.