R
[RS99] Jean-François Raskin and Pierre-Yves Schobbens. The Logic of Event-Clocks: Decidability, Complexity and Expressiveness. Journal of Automata, Languages and Combinatorics 4(3):247-286. 1999. 
@article{jalc4(3)-RS,
  author =              {Raskin, Jean-Fran{\c c}ois and Schobbens,
                         Pierre-Yves},
  title =               {The Logic of Event-Clocks: Decidability, Complexity
                         and Expressiveness},
  journal =             {Journal of Automata, Languages and Combinatorics},
  volume =              {4},
  number =              {3},
  pages =               {247-286},
  year =                {1999},
}
List of authors