Naskar S, Bhoi D, Garg H, Dehran M, Trikha A, Ansari MT.  A comparison of analgesic efficacy and safety of clonidine and methylprednisolone as additives to 0.25% ropivacaine in stellate ganglion block for the treatment of complex regional pain syndrome: a prospective randomised single blind study.  Korean J Pain 2023;36:216-229.  https://doi.org/10.3344/kjp.22299