Comparison of two low dose local anesthetics in combination with morphine for spinal anesthesia for total knee arthroplasty - Gulec, Handan; Ozayar, Esra; Alkan, Asli; Kacan, Merve; Babayigit, Munire; Kurtay, Aysun; Demirkale, Ismail; Horasanli, Eyup (Anaesthesia, Pain & Intensive Care, 2020)