@article{Li_2011,
    doi = {10.1016/j.automatica.2011.06.017},
    url = {https://doi.org/10.1016%2Fj.automatica.2011.06.017},
    year = {2011},
    month = {sep},
    publisher = {Elsevier {BV}},
    volume = {47},
    number = {9},
    pages = {2094--2098},
    author = {Duan Li and Xiaoling Sun and Jianjun Gao and Shenshen Gu and Xiaojin Zheng},
    title = {Reachability determination in acyclic Petri nets by cell enumeration approach},
    journal = {Automatica}
}

@article{Li_2011, doi = {10.1016/j.automatica.2011.06.017}, url = {https://doi.org/10.1016%2Fj.automatica.2011.06.017}, year = {2011}, month = {sep}, publisher = {Elsevier {BV}}, volume = {47}, number = {9}, pages = {2094--2098}, author = {Duan Li and Xiaoling Sun and Jianjun Gao and Shenshen Gu and Xiaojin Zheng}, title = {Reachability determination in acyclic Petri nets by cell enumeration approach}, journal = {Automatica} }