Kalashnykova, M. N., and E. G. Peretyatko. “Integrity of Biological Properties of Enterococcus Bacteria After Cryopreservation”. Problems of Cryobiology and Cryomedicine, vol. 18, no. 1, May 2008, pp. 34-36, http://cryo.org.ua/journal/index.php/probl-cryobiol-cryomed/article/view/445.