Mitchell, J. G.; Terrell, D. J. (1985): Downhole variation of potassium, inert gas abundance, and apparent K-Ar age in basalts from the Costa Rica Rift, Hole 504B, Leg 83, Deep Sea Drilling Project. Texas A & M University, Ocean Drilling Program, College Station, TX, United States, In: Anderson, Roger N., Honnorez, Jose, Adamson, Andrew C., Alt, Jeffrey C., Emmermann, Rolf, Kempton, Pamela D., Kinoshita, Hajimu, Leverne, Christine, Mottl, Michael J., Newmark, Robin L., Becker, Keir, Initial reports of the Deep Sea Drilling Project, covering Leg 83 of the cruises of the Drilling Vessel Glomar Challenger, Balboa, Panama to Balboa, Panama, November 1981- January 1982, 83, 305-312, georefid:1985-059452