@article{vegetti_henning_leone_2002,  title={An object-oriented model for complex bills of materials in process industries},  volume={19},  ISSN={0104-6632},  url={https://doi.org/10.1590/S0104-66322002000400019},  DOI={10.1590/S0104-66322002000400019},  number={4},  journal={Brazilian Journal of Chemical Engineering},  publisher={Brazilian Society of Chemical Engineering},  author={Vegetti, M. and Henning, G.P. and Leone, H.P.},  year={2002},  month={Oct},  pages={491–497} }