@article{portela_simpson_1997, title={Markers, Cofactors and Staging Systems in the Study of HIV Disease Progression: A Review}, volume={92}, ISSN={0074-0276}, url={https://doi.org/10.1590/S0074-02761997000400001}, DOI={10.1590/S0074-02761997000400001}, number={4}, journal={Memórias do Instituto Oswaldo Cruz}, publisher={Instituto Oswaldo Cruz, Ministério da Saúde}, author={Portela, MC and Simpson, KN}, year={1997}, month={July}, pages={437–457} }