1H-Pyrazole-3-carboxylic acid, 4,5-dihydro-5-oxo-1-phenyl-, 5-Oxo-1-phenyl-2-pyrazolin-3-carboxylic acid, 5-oxo-1-phenyl-4H-pyrazole-3-carboxylic acid; 1-Phenyl-3-carboxy-5-pyrazolone 3-Carboxy-1-phenyl-2-pyrazolin-5-one; 1-Phenyl-5-pyrazolone-3-carboxylic acid (PCP);