1. Păun, G.: A new generative device: valence grammars. Rev. Roumaine Math. Pures Appl. XXV(6), 911–924 (1980)
2. Csuhaj–Varjú, E., Dassow, J.: On cooperating/distributed grammar systems. J. Inf. Process. Cybern. EIK (formerly Elektron. Inf. verarb. Kybern.) 26(1/2), 49–63 (1990)
3. Csuhaj–Varjú, E., Dassow, J., Kelemen, J., Păun, G.: Grammar Systems: A Grammatical Approach to Distribution and Cooperation. Gordon and Breach, London (1994)
4. Dassow, J., Păun, G.: Cooperating/distributed grammar systems with registers. Foundations of Control Engineering 15(1), 1–38 (1990)
5. Vicolov, S.: Cooperating/distributed grammar systems with registers: the regular case. Computers and Artificial Intelligence 12(1), 89–98 (1993)