1. Descriptions of eight new USGS rock standards;Flanagan;U.S. Geological Survey Professional Paper,1976
2. L. Shapiro 1967 Rapid analysis of rocks and minerals by a single-solution method Geological Survey Research B187 B191
3. Rapid analysis of silicate carbonate and phosphate rocks, revised edition;Shapiro;U.S. Geological Survey Bulletin,1975
4. The absorptiometric determination of aluminum in water;Dougan;A comparison of some chromogenic reagents and the development of an improved method, Analyst,1974