Leen Lambers Hartmut Ehrig Fernando Orejas Efficient Conflict Detection in Graph Transformation Systems by Essential Critical Pairs. 17-26 2008 211 Electr. Notes Theor. Comput. Sci. http://dx.doi.org/10.1016/j.entcs.2008.04.026 db/journals/entcs/entcs211.html#LambersEO08