Verma , S. P. «Improved Concentration Data in Two International Geochemical Reference Materials (USGS Basalt BIR-1 and GSJ Peridotite JP-1) by Outlier Rejection». Geofísica Internacional, vol. 37, n.º 3, julio de 1998, pp. 215-50, doi:10.22201/igeof.00167169p.1998.37.3.394.