@article{dobrev2008using,
  title={Using scattered mobile agents to locate a black hole in an un-oriented ring with tokens},
  author={Dobrev, Stefan and Santoro, Nicola and Shi, Wei},
  journal={International Journal of Foundations of Computer Science},
  volume={19},
  number={06},
  pages={1355--1372},
  year={2008},
  publisher={World Scientific}
}