abs-0907-5120'

@inproceedings{DBLP:journals/corr/abs-0907-5120,
  author    = {Rudolf Freund and
               Andreas Klein and
               Martin Kutrib},
  title     = {On the Number of Membranes in Unary P Systems},
  booktitle = {DCFS},
  year      = {2009},
  pages     = {101-109},
  ee        = {http://dx.doi.org/10.4204/EPTCS.3.9},
  crossref  = {DBLP:journals/corr/abs-0907-5257},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}

@proceedings{DBLP:journals/corr/abs-0907-5257,
  editor    = {J{\"u}rgen Dassow and
               Giovanni Pighizzini and
               Bianca Truthe},
  title     = {Proceedings Eleventh International Workshop on Descriptional
               Complexity of Formal Systems},
  booktitle = {DCFS},
  series    = {EPTCS},
  volume    = {3},
  year      = {2009},
  ee        = {http://dx.doi.org/10.4204/EPTCS.3},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}