@article{Elston_2004,
    doi = {10.1016/j.tcs.2003.09.007},
    url = {https://doi.org/10.1016%2Fj.tcs.2003.09.007},
    year = {2004},
    month = {jun},
    publisher = {Elsevier {BV}},
    volume = {320},
    number = {2-3},
    pages = {175--185},
    author = {Gillian Z. Elston and Gretchen Ostheimer},
    title = {On groups whose word problem is solved by a{\textasciitilde}counter automaton},
    journal = {Theoretical Computer Science}
}

@article{Elston_2004, doi = {10.1016/j.tcs.2003.09.007}, url = {https://doi.org/10.1016%2Fj.tcs.2003.09.007}, year = {2004}, month = {jun}, publisher = {Elsevier {BV}}, volume = {320}, number = {2-3}, pages = {175--185}, author = {Gillian Z. Elston and Gretchen Ostheimer}, title = {On groups whose word problem is solved by a{\textasciitilde}counter automaton}, journal = {Theoretical Computer Science} }