@article{mcgregor_eden_1991,  title={Geomorphology and land development in the Maraca area of northern Roraima, Brazil.},  volume={21},  ISSN={0044-5967},  url={https://doi.org/10.1590/1809-43921991211407},  DOI={10.1590/1809-43921991211407},  journal={Acta Amazonica},  publisher={Instituto Nacional de Pesquisas da Amazônia},  author={McGregor, Duncan F. M. and Eden, Michael J.},  year={1991},  pages={391–407} }