I. Krushinskaya, R. Boltnev, I. Bykhalo, A. Pelmenev, V. Khmelenko, and D. Lee, “Optical spectroscopy and current detection during warm-up and destruction of impurity-helium condensates”, Rec.Contr.Phys., vol. 2015, no. 3, pp. 64–65, Jan. 2015.