@article{van kampen_1998,  title={Remarks on Non-Markov Processes},  volume={28},  ISSN={0103-9733},  url={https://doi.org/10.1590/S0103-97331998000200003},  DOI={10.1590/S0103-97331998000200003},  number={2},  journal={Brazilian Journal of Physics},  publisher={Sociedade Brasileira de Física},  author={van Kampen, N.G.},  year={1998},  month={Jun},  pages={90–96} }