@article{czirok1996formation, title={Formation of complex bacterial colonies via self-generated vortices}, author={Czir{\'o}k, Andr{\'a}s and Ben-Jacob, Eshel and Cohen, Inon and Vicsek, Tam{\'a}s}, journal={Physical Review E}, volume={54}, number={2}, pages={1791}, year={1996}, publisher={APS} }