@article{Hajek,
    Author = {Hajek, Petr},
    File = {Arithmetical hierarchy and complexity of computation - Hajek (0) (0) - a - a - q.pdf},
    ISSN = {0304-3975},
    Journal = {Theoretical Computer Science},
    Number = {2},
    Pages = {227 - 237},
    Title = {Arithmetical hierarchy and complexity of computation},
    URL = {http://www.sciencedirect.com/science/article/pii/030439757990046X},
    Volume = {8},
    Year = {1979},
    bdsk-url-1 = {http://www.sciencedirect.com/science/article/pii/030439757990046X},
    bdsk-url-2 = {http://dx.doi.org/10.1016/0304-3975(79)90046-X},
    date-added = {2013-03-27 14:44:07 +0000},
    date-modified = {2013-03-27 14:44:07 +0000},
    doi = {10.1016/0304-3975(79)90046-X}
}

@article{Hajek, Author = {Hajek, Petr}, File = {Arithmetical hierarchy and complexity of computation - Hajek (0) (0) - a - a - q.pdf}, ISSN = {0304-3975}, Journal = {Theoretical Computer Science}, Number = {2}, Pages = {227 - 237}, Title = {Arithmetical hierarchy and complexity of computation}, URL = {http://www.sciencedirect.com/science/article/pii/030439757990046X}, Volume = {8}, Year = {1979}, bdsk-url-1 = {http://www.sciencedirect.com/science/article/pii/030439757990046X}, bdsk-url-2 = {http://dx.doi.org/10.1016/0304-3975(79)90046-X}, date-added = {2013-03-27 14:44:07 +0000}, date-modified = {2013-03-27 14:44:07 +0000}, doi = {10.1016/0304-3975(79)90046-X} }