SILICA SUPPORTED PERCHLORIC ACID (HCLO4-SIO2) AS ECOFRIENDLY REUSABLE CATALYSTS FOR GREEN SYNTHESIS OF TETRAHYDROBENZO[B]PYRAN DERIVATIVES BY GRINDING METHOD. IJFANS. 2022;11(12):3348-3353. Accessed August 24, 2026. http://www.ijfans.org/index.php/Journal/article/view/13213