Dadan Prayogo; Bernadus Sadu; Utomo Wicaksono; Fitri Gunawati. ADDITION OF DEEP CROSS-FRICTION MASSAGE IS BETTER THAN SLOW STROKE BACK MASSAGE AFTER MCKENZIE EXERCISE TO IMPROVE FUNCTIONAL ABILITY AND WORK PRODUCTIVITY OF STONE BREAKERS WITH NON-SPECIFIC LOW BACK PAIN. IJSS 2022, 2, 1483-1490.