Tsymbalyuk, V. I., I. B. Tretyak, N. A. Sapon, S. B. Krychun, and V. I. Prykhodko. “The Problem of Pain Investigation in the Literature of CIS Countries”. Ukrainian Neurosurgical Journal, no. 4, Dec. 2005, pp. 4-10, doi:10.25305/unj.128590.