Vegetation dynamics during the late Pleistocene in the Barreirinhas region, Maranhão State, Northeastern Brazil, based on carbon isotopes in soil organic matter - Pessenda, Luiz Carlos Ruiz; Ribeiro, Adauto de Souza; Gouveia, Susy Eli Marques; Aravena, Ramon; Boulet, Renné Georges Leon; Bendassolli, Jose Albertino (Quaternary Research, 2004)