TY - RPRT TI - U-Pb isotope systematics and apparent ages of uranium ores, Ambrosia Lake and Smith Lake districts, Grants mineral belt, New Mexico AU - K.R. Ludwig AU - K. R. Simmons AU - J.D. Webster PY - 1984 DO - 10.2113/gsecongeo.79.2.322 UR - https://pubs.usgs.gov/publication/70014077 ID - 70014077 ER -