Li, L., G. Keller, T. Adatte, and W. Stinnesbeck. (2000) 2000. “Late Cretaceous Sea-Level Changes in Tunisia: A Multi-Disciplinary Approach”. Journal of the Geological Society 157 (2): 447-58. doi:10.1144/jgs.157.2.447. Reference Link
Li, L., and G. Keller. 1998. “Diversification and Extinction in Campanian-Maastrichtian Planktic Foraminifera of Northwestern Tunisia”. Eclogae Geologicae Helvetiae 91 (1). Referenced from serials.unibo.it: Diversification and extinction in Campanian-Maastrichtian planktic foraminifera of northwestern Tunisia. Reference Link
Keller, G., L. Li, and N. MacLeod. (1996) 1995. “The Cretaceous Tertiary Boundary Stratotype Section at El Kef, Tunisia: How Catastrophic Was the Mass Extinction?”. Palaeogeography, Palaeoclimatology, Palaeoecology 119 (3-4): 221-54. doi:10.1016/0031-0182(95)00009-7. Reference Link