STUDYING THE POSSIBILITY OF APPLYING SIX SIGMA STRATEGY TO INCREASE PERFORMANCE EFFICIENCY AND QUALITY OF HEALTH SECTOR SERVICES. Wor.econo. and fin. Bul. [Internet]. 2022 Apr. 8 [cited 2026 Apr. 18];9:25-39. Available from: https://www.scholarexpress.net/index.php/wefb/article/view/775