@article{szajnbock_lorenzi_rodrigues jr._zantut_poggetti_steinman_birolini_1996,  title={Gallstone ileus as a cause of upper intestinal obstruction},  volume={114},  ISSN={1516-3180},  url={https://doi.org/10.1590/S1516-31801996000400009},  DOI={10.1590/S1516-31801996000400009},  number={4},  journal={Sao Paulo Medical Journal},  publisher={Associação Paulista de Medicina - APM},  author={Szajnbock, Israel and Lorenzi, Fernando and Rodrigues Jr., Aldo Junqueira and Zantut, Luis Fernando Correa and Poggetti, Renato Sérgio and Steinman, Eliana and Birolini, Dario},  year={1996},  month={Jul},  pages={1239–1243} }