@article{el gaddal_1989,  title={Control of schistosomiasis in the Gezira},  volume={84},  ISSN={0074-0276},  url={https://doi.org/10.1590/S0074-02761989000500012},  DOI={10.1590/S0074-02761989000500012},  journal={Memórias do Instituto Oswaldo Cruz},  publisher={Instituto Oswaldo Cruz, Ministério da Saúde},  author={El Gaddal, A. A.},  year={1989},  pages={117–123} }