@article{Thatcher:1967:CDT:1739942.1740120,
    Address = {Orlando, FL, USA},
    Author = {Thatcher, J. W.},
    File = {Characterizing derivation trees of context-free grammars through a generalization of finite automata theory - Thatcher (0) (0) - a - a - c.pdf},
    ISSN = {0022-0000},
    Journal = {J. Comput. Syst. Sci.},
    Keywords = {context-free grammars},
    Month = {December},
    Number = {4},
    Pages = {317--322},
    Publisher = {Academic Press, Inc.},
    Title = {Characterizing derivation trees of context-free grammars through a generalization of finite automata theory},
    URL = {http://dx.doi.org/10.1016/S0022-0000(67)80022-9},
    Volume = {1},
    Year = {1967},
    acmid = {1740120},
    bdsk-url-1 = {http://dx.doi.org/10.1016/S0022-0000(67)80022-9},
    date-added = {2013-04-01 19:02:45 +0000},
    date-modified = {2013-04-01 19:03:26 +0000},
    issue_date = {December, 1967},
    numpages = {6},
    doi = {10.1016/S0022-0000(67)80022-9}
}

@article{Thatcher:1967:CDT:1739942.1740120, Address = {Orlando, FL, USA}, Author = {Thatcher, J. W.}, File = {Characterizing derivation trees of context-free grammars through a generalization of finite automata theory - Thatcher (0) (0) - a - a - c.pdf}, ISSN = {0022-0000}, Journal = {J. Comput. Syst. Sci.}, Keywords = {context-free grammars}, Month = {December}, Number = {4}, Pages = {317--322}, Publisher = {Academic Press, Inc.}, Title = {Characterizing derivation trees of context-free grammars through a generalization of finite automata theory}, URL = {http://dx.doi.org/10.1016/S0022-0000(67)80022-9}, Volume = {1}, Year = {1967}, acmid = {1740120}, bdsk-url-1 = {http://dx.doi.org/10.1016/S0022-0000(67)80022-9}, date-added = {2013-04-01 19:02:45 +0000}, date-modified = {2013-04-01 19:03:26 +0000}, issue_date = {December, 1967}, numpages = {6}, doi = {10.1016/S0022-0000(67)80022-9} }