@article(barany12,
 author       = "Vince B{\'a}r{\'a}ny and Mikolaj Bojanczyk",
 year         = "2012",
 title        = "Finite satisfiability for guarded fixpoint logic",
 journal      = "Inf. Process. Lett.",
 volume       = "112",
 number       = "10",
 pages        = "371--375",
 doi          = "10.1016/j.ipl.2012.02.005",
)
@article(Berger66,
 author       = "R. Berger",
 year         = "1966",
 title        = "The undecidability of the domino problem",
 journal      = "Mem.~AMS",
 volume       = "66",
)
@book(BdRV01,
 author       = "Patrick Blackburn and Maarten de Rijke and Yde Venema",
 year         = "2001",
 title        = "Modal Logic",
 series       = "Cambridge Tracts in Theoretical Comp. Sc.",
 volume       = "53",
 publisher    = "Cambridge University Press",
 address      = "Cambridge",
)
@book(BorgerGG1997,
 author       = "Egon B{\"o}rger and Erich Gr{\"a}del and Yuri Gurevich",
 year         = "1997",
 title        = "The Classical Decision Problem",
 series       = "Perspectives in Mathematical Logic",
 publisher    = "Springer",
)
@inproceedings(G06,
 author       = "Igor Gorbunov",
 year         = "2006",
 title        = "A decidable modal logic that is finitely undecidable",
 editor       = "Guido Governatori and Ian M. Hodkinson and Yde Venema",
 booktitle    = "Advances in Modal Logic",
 publisher    = "College Publications",
 pages        = "247--258",
 url          = "http://www.aiml.net/volumes/volume6/Gorbunov.ps",
)
@article(gradel,
 author       = "Erich Gr{\"a}del",
 year         = "1999",
 title        = "On the restraining power of guards",
 journal      = "J. Symbolic Logic",
 volume       = "64",
 pages        = "1719--1742",
 doi          = "10.2307/2586808",
)
@inproceedings(fixed,
 author       = "Erich Gr{\"a}del and Igor Walukiewicz",
 year         = "1999",
 title        = "Guarded fixed point logic",
 booktitle    = "Fourteenth Annual IEEE Symposium on Logic in Computer Science",
 pages        = "45--54",
 doi          = "10.1109/LICS.1999.782585",
)
@article(GK72,
 author       = "Yu. Sh. Gurevich and I. O. Koryakov",
 year         = "1972",
 title        = "Remarks on Berger's paper on the domino problem",
 journal      = "Siberian Mathematical Journal",
 volume       = "13",
 pages        = "319--321",
 doi          = "10.1007/BF00971620",
)
@article(HS96,
 author       = "Edith Hemaspaandra",
 year         = "1996",
 title        = "The Price of Universality",
 journal      = "Notre Dame Journal of Formal Logic",
 volume       = "37",
 pages        = "174--203",
 doi          = "10.1305/ndjfl/1040046086",
)
@inproceedings(HS08,
 author       = "Edith Hemaspaandra and Henning Schnoor",
 year         = "2008",
 title        = "On the Complexity of Elementary Modal Logics",
 editor       = "Susanne Albers and Pascal Weil",
 booktitle    = "STACS",
 series       = "LIPIcs",
 volume       = "1",
 publisher    = "Schloss Dagstuhl - Leibniz-Zentrum fuer Informatik, Germany",
 pages        = "349--360",
 doi          = "10.4230/LIPIcs.STACS.2008.1356",
)
@inproceedings(HS11,
 author       = "Edith Hemaspaandra and Henning Schnoor",
 year         = "2011",
 title        = "A Universally Defined Undecidable Unimodal Logic",
 editor       = "Filip Murlak and Piotr Sankowski",
 booktitle    = "MFCS",
 series       = "Lecture Notes in Computer Science",
 volume       = "6907",
 publisher    = "Springer",
 pages        = "364--375",
 doi          = "10.1007/978-3-642-22993-0\_34",
)
@inproceedings(KMO11,
 author       = "Emanuel Kiero\'{n}ski and Jakub Michaliszyn and Jan Otop",
 year         = "2011",
 title        = "Modal Logics Definable by Universal Three-Variable Formulas",
 editor       = "Supratik Chakraborty and Amit Kumar",
 booktitle    = "FSTTCS",
 series       = "LIPIcs",
 volume       = "13",
 publisher    = "Schloss Dagstuhl - Leibniz-Zentrum fuer Informatik",
 pages        = "264--275",
 doi          = "10.4230/LIPIcs.FSTTCS.2011.264",
)
@inproceedings(self,
 author       = "Emanuel Kiero\'{n}ski and Jakub Michaliszyn and Ian Pratt-Hartmann and Lidia Tendera",
 year         = "2012",
 title        = "Two-variable first-order logic with equivalence closure",
 booktitle    = "LICS '12: Proceedings of the 29th IEEE symposium on Logic in Computer Science",
)
@inproceedings(KT07,
 author       = "Emanuel Kieronski and Lidia Tendera",
 year         = "2007",
 title        = "On Finite Satisfiability of the Guarded Fragment with Equivalence or Transitive Guards",
 editor       = "Nachum Dershowitz and Andrei Voronkov",
 booktitle    = "LPAR",
 series       = "Lecture Notes in Computer Science",
 volume       = "4790",
 publisher    = "Springer",
 pages        = "318--332",
 doi          = "10.1007/978-3-540-75560-9\_24",
)
@inproceedings(m08,
 author       = "Jakub Michaliszyn",
 year         = "2009",
 title        = "Decidability of the Guarded Fragment with the Transitive Closure",
 editor       = "Susanne Albers and Alberto Marchetti-Spaccamela and Yossi Matias and Sotiris E. Nikoletseas and Wolfgang Thomas",
 booktitle    = "ICALP (2)",
 series       = "Lecture Notes in Computer Science",
 volume       = "5556",
 publisher    = "Springer",
 pages        = "261--272",
 doi          = "10.1007/978-3-642-02930-1\_22",
)
@inproceedings(KM12,
 author       = "Jakub Michaliszyn and Emanuel Kiero\'{n}ski",
 year         = "2012",
 title        = "Finite Satisfiability of Universally-Horn Definable Modal Logics",
 booktitle    = "Accepted to AIML 2012",
 url          = "http://www.ii.uni.wroc.pl/~jmi/papers/eml-finite12.pdf",
)
@inproceedings(lics12,
 author       = "Jakub Michaliszyn and Jan Otop",
 year         = "2012",
 title        = "Decidable Elementary Modal Logics",
 booktitle    = "LICS '12: Proceedings of the 29th IEEE symposium on Logic in Computer Science",
 url          = "http://www.ii.uni.wroc.pl/~jmi/papers/horn.pdf",
)
@inproceedings(MPS10,
 author       = "Angelo Montanari and Gabriele Puppis and Pietro Sala",
 year         = "2010",
 title        = "Maximal Decidable Fragments of {H}alpern and {S}hoham's Modal Logic of Intervals.",
 editor       = "Samson Abramsky and Cyril Gavoille and Claude Kirchner and Friedhelm Meyer auf der Heide and Paul G. Spirakis",
 booktitle    = "ICALP (2)",
 series       = "Lecture Notes in Computer Science",
 volume       = "6199",
 publisher    = "Springer",
 pages        = "345--356",
 doi          = "10.1007/978-3-642-14162-1\_29",
)
@article(fodwa,
 author       = "Michael Mortimer",
 year         = "1975",
 title        = "On languages with two variables",
 journal      = "Mathematical Logic Quarterly",
 volume       = "21",
 number       = "1",
 pages        = "135--140",
 doi          = "10.1002/malq.19750210118",
)
@article(Otto,
 author       = "Martin Otto",
 year         = "1998",
 title        = "Two Variable First-Order Logic over Ordered Domains",
 journal      = "Journal of Symbolic Logic",
 volume       = "66",
 pages        = "685--702",
 doi          = "10.2307/2695037",
)
@article(sahlqvist,
 author       = "Henrik Sahlqvist",
 year         = "1973",
 title        = "Completeness and correspondence in the first and second order semantics for modal logic",
 journal      = "Proceedings of the Third Scandinavian Logic Symposium",
 doi          = "10.1016/S0049-237X(08)70728-6",
)
@article(Var97,
 author       = "M. Y. Vardi",
 year         = "1997",
 title        = "Why is modal logic so robustly decidable?",
 journal      = "DIMACS Series in Discrete Mathematics and Theoretical Computer Science,",
 volume       = "31",
 pages        = "149--184",
)