@article{RusSul:76,
  journal = {Stud. Cerc. Mat.},
  volume = {28},
  title = {On the notion of representation between operator schemes defined by
           context-free grammars},
  year = {1976},
  fjournal = {Studii \c si Cercet\u ari Matematice},
  pages = {79--94},
  number = {1},
  author = {Rus, Teodor and Sularia, Mircea},
}