@article{psaker_2004,  title={Inclusive photoproduction of lepton pairs in the parton model},  volume={34},  ISSN={0103-9733},  url={https://doi.org/10.1590/S0103-97332004000500064},  DOI={10.1590/S0103-97332004000500064},  number={3a},  journal={Brazilian Journal of Physics},  publisher={Sociedade Brasileira de Física},  author={Psaker, A.},  year={2004},  month={Sep},  pages={944–947} }