W. Ali, H. Youssef, A. Abbas, P. Roshdy, A. Imbaby, and M. Abdelrady, “Intrathecal bupivacaine with fentanyl compared to levobupivacaine with fentanyl for painless labor: a double-blind, randomized clinical trial”, apic, vol. 27, no. 4, pp. 478-484, Jun. 2023.