S. V. Repina, O. A. Nardid, E. D. Rozanova, L. V. Tsymbal, M. I. Schetinsky, and E. I. Naumenko, “EPR-Study of Redox Reactions of Human Placenta Aqueous-Saline Extracts: Storage Temperature and Extraction Time Effects”, Probl Cryobiol Cryomed, vol. 15, no. 4, pp. 591–598, Dec. 2005.