Ledbetter, Michael T.; Stormer, John C., Jr. (1980): Tephrachronology of late Miocene to Recent Central American explosive eruptions using DSDP Leg 68 hydraulic piston cores. Geological Society of America (GSA), Boulder, CO, United States, In: The Geological Society of America, 93rd annual meeting, 12 (7), 469-470, georefid:1984-024826