Ulbrich, H. H., et al. “QUALITY CONTROL OF ANALYTICAL ROUTINES FOR WHOLE-ROCK GEOCHEMISTRY: I: PARTICIPATION OF THE CHEMISTRY AND ICP-OES LABORATORY, INSTITUTE OF GEOSCIENCES, UNIVERSITY OF SÃO PAULO, IN THE INTERNATIONAL PROFICIENCY ROUNDS GEOPT 2, 3 AND 4”. Geochimica Brasiliensis, vol. 16, no. 2, Dec. 2011, https://geobrasiliensis.org.br/geobrasiliensis/article/view/190.