@article{Cook:1971:CPM:321623.321625,
    Address = {New York, NY, USA},
    Author = {Cook, Stephen A.},
    File = {Characterizations of Pushdown Machines in Terms of Time-Bounded Computers - Cook (0) (0) - a - a - d.pdf},
    ISSN = {0004-5411},
    Journal = {J. ACM},
    Month = {January},
    Number = {1},
    Pages = {4--18},
    Publisher = {ACM},
    Title = {Characterizations of Pushdown Machines in Terms of Time-Bounded Computers},
    URL = {http://doi.acm.org/10.1145/321623.321625},
    Volume = {18},
    Year = {1971},
    acmid = {321625},
    bdsk-url-1 = {http://doi.acm.org/10.1145/321623.321625},
    bdsk-url-2 = {http://dx.doi.org/10.1145/321623.321625},
    date-added = {2014-09-15 15:12:17 +0000},
    date-modified = {2014-09-15 15:12:17 +0000},
    issue_date = {Jan. 1971},
    numpages = {15},
    doi = {10.1145/321623.321625}
}

@article{Cook:1971:CPM:321623.321625, Address = {New York, NY, USA}, Author = {Cook, Stephen A.}, File = {Characterizations of Pushdown Machines in Terms of Time-Bounded Computers - Cook (0) (0) - a - a - d.pdf}, ISSN = {0004-5411}, Journal = {J. ACM}, Month = {January}, Number = {1}, Pages = {4--18}, Publisher = {ACM}, Title = {Characterizations of Pushdown Machines in Terms of Time-Bounded Computers}, URL = {http://doi.acm.org/10.1145/321623.321625}, Volume = {18}, Year = {1971}, acmid = {321625}, bdsk-url-1 = {http://doi.acm.org/10.1145/321623.321625}, bdsk-url-2 = {http://dx.doi.org/10.1145/321623.321625}, date-added = {2014-09-15 15:12:17 +0000}, date-modified = {2014-09-15 15:12:17 +0000}, issue_date = {Jan. 1971}, numpages = {15}, doi = {10.1145/321623.321625} }