1(3H)-Isobenzofuranone, 3,3-bis(4-hydroxy-1-naphthalenyl)-;à-naphtholphthalein;3,3-bis(4-hydroxy-1-naphthyl)phthalide;A-NAPHTHOLPHTHALEIN PRACTICAL GRADE;ALPHA-NAPHTHOLPHTHALEIN INDICATOR;1-NAPHTHOLPHTHALEIN, INDICATOR;ALPHA-NAPHTHOLPHTHALEIN(0.1% IN CA. 50% ETHANOL)[FOR PH DETERMINATION];alpha-Naphtholphthalein, indicator, pure