1. Helium determinations as an exploration technique at the Ambrosia Lake Uranium District, McKinley County, New Mexico;Brady;U.S. Geol. Surv. Open File Rep. 77-669,1977
2. Helium determinations in mineral exploration;Butt,1984
3. Gases and trace elements in soils at the North Silver Bell deposit, Pima County, Arizona;Butt,1985
4. Dissolved helium in groundwater: A possible method for uranium and thorium prospecting;Clarke;Econ. Geol.,1973
5. Aeration, respiration and atmosphere;De Jong,1979