Carstic working standard development for ''delta' POT. 13'C e ''delta' POT. 18'O IRMS analysis - Antunes Junior, Osmar; Hollanda, Maria Helena Bezerra Maia de; Cruz, Francisco W; Mancini, Luís Henrique; Sial, Alcides Nobrega; Van Hale, Robert (South American Symposium on Isotope Geology, 2014)