E
[ER09] Andrzej Ehrenfeucht and Grzegorz Rozenberg. Introducing Time in Reaction Systems. Theoretical Computer Science 410(4-5). Elsevier, February 2009. 
@article{tcs410(4-5)-ER,
  author =              {Ehrenfeucht, Andrzej and Rozenberg, Grzegorz},
  title =               {Introducing Time in Reaction Systems},
  publisher =           {Elsevier},
  journal =             {Theoretical Computer Science},
  volume =              {410},
  number =              {4-5},
  year =                {2009},
  month =               feb,
  doi =                 {10.1016/j.tcs.2008.09.043},
}
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