@article{Thatcher_1970,
    doi = {10.1016/s0022-0000(70)80017-4},
    url = {https://doi.org/10.1016%2Fs0022-0000%2870%2980017-4},
    year = {1970},
    month = {aug},
    publisher = {Elsevier {BV}},
    volume = {4},
    number = {4},
    pages = {339--367},
    author = {James W. Thatcher},
    title = {Generalized2 sequential machine maps},
    journal = {Journal of Computer and System Sciences}
}

@article{Thatcher_1970, doi = {10.1016/s0022-0000(70)80017-4}, url = {https://doi.org/10.1016%2Fs0022-0000%2870%2980017-4}, year = {1970}, month = {aug}, publisher = {Elsevier {BV}}, volume = {4}, number = {4}, pages = {339--367}, author = {James W. Thatcher}, title = {Generalized2 sequential machine maps}, journal = {Journal of Computer and System Sciences} }