1. Tracing fluids between wells;Heck;Producers Monthly,1954
2. Research to assay rain and surface for natural tritium content;Libby,1954
3. Investigation of resistivity during flooding of the Bradford sand;Licastro;Producers Monthly,1951
4. Tracing flow of fluids and gases beneath ground;Plummer;Oil Gas J.,1945
5. U. S. Geol. Surv. Wate Supply Paper;Slichter,1905