Which sedation method is appropriate for spinal anesthesia: propofol or ketamine-propofol combination - Güleç, Handan; Tutal, Zehra Baykal; Şahap, Mehmet; Babayiğit, Münire; İnceöz, Hansa and Kurtay, Aysun and Horasanlı, Eyüp (Anaesthesia, Pain & Intensive Care, 2019)