@article {, title = {Verifying a P system generating squares}, journal = {Romanian Journal of Information Science and Technology}, volume = {5}, year = {2002}, pages = {181-191}, publisher = {EDITURA ACADEMIEI ROM{\^A}NE}, address = {Bucure{\c s}ti, Rom{\^a}nia}, keywords = {Formal Verification, Membrane computing, Natural computing}, issn = {1453-8245}, url = {http://www.cs.us.es/~marper/investigacion/resumen-cuadrados.pdf}, author = {Mario J. P{\'e}rez-Jim{\'e}nez and Fernando Sancho-Caparrini} }