Islam, S. R.; Begum, H.; Kamal, M. M.; Bhuiyan, M. S. A.; Khatun, U. S. Effects of Ketamine Hydrochloride (preservative Free) and Fentanyl Citrate Added to Low Dose Hyperbaric Bupivacaine for Sub-Arachnoid Block in Lower Uterine Caesarian Section – a Comperative Study. j Bangladesh Soc Anaesthesiologists 2014, 24, 53-59.