@article{articledbccc374,
title   = {Determination of thorium concentrations and activity ratios in silicate rocks by alpha spectrometry},
author = {Santos, R.N. dos and Marques, Leila Soares and Nicolai, Silvia Helena de Araujo and Brenha Ribeiro, Fernando},
year = {2004},
doi = {10.1016/j.apradiso.2003.09.013},
journal   = {Applied Radiation and Isotopes}
}