Sergio Antoy Daniel W. Brown Su-Hui Chiang Lazy Context Cloning for Non-Deterministic Graph Rewriting. 3-23 2007 176 Electr. Notes Theor. Comput. Sci. 1 http://dx.doi.org/10.1016/j.entcs.2006.10.026 db/journals/entcs/entcs176.html#AntoyBC07