1. A. S. Holevo (Kholevo), Statistical Structure of Quantum Theory (IKI, Moscow-Izhevsk, 2003) [in Lect. Notes in Phys., New Series m: Monographs (Springer-Verlag, Berlin, 2001), Vol. 67].
2. A. Wehrl, Rev. Modern Phys. 50(2), 221 (1978).
3. M. E. Shirokov, Teor. Veroyatnost. Primenen. 53(4), 732 (2008) [Theory Probab. Appl. 53 (4), 648 (2009)].
4. G. Lindblad, Comm. Math. Phys. 39(2), 111 (1974).
5. M. E. Shirokov, Izv. Ross. Akad. Nauk Ser. Mat. 70(6), 193 (2006) [Russian Acad. Sci. Izv. Math. 70 (6), 1265 (2006)].