Comparison of Effect of Meperidine Versus Fentanyl as an Adjuvant to Epidural Bupivacaine on Duration of Labor: A Randomized Controlled Study - Nataj Majd, Masoomeh; Farid Mojtahedi, Maryam; Taheri, Arman; Sanatkar, Mehdi; Ali Nazemian Yazdi, Nader (Acta Medica Iranica, 2022)