@article{valois b. jr_oliveira_2011,  title={Recommender systems in social networks},  volume={8},  ISSN={1807-1775},  url={https://doi.org/10.4301/S1807-17752011000300009},  DOI={10.4301/S1807-17752011000300009},  number={3},  journal={JISTEM - Journal of Information Systems and Technology Management},  publisher={TECSI Laboratório de Tecnologia e Sistemas de Informação - FEA/USP},  author={Valois B. Jr, Cleomar and Oliveira, Marcius Armada de},  year={2011},  month={Sep},  pages={681–716} }