1. G. Gearger, Quantum Information: An Overview, Springer-Verlag, Berlin (2006).
2. R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, Rev. Mod. Phys., 81, 865 (2009).
3. C. H. Bennett, D. P. DiVincenzo, J. A. Smolin, and W. K. Wootters, Phys. Rev. A, 54, 3824 (1996).
4. M. Horodecki, Quantum Inform. Comput., 1, iss. 1, p. 3 (2001).
5. W. K. Wootters, Quantum Inform. Comput., 1, iss. 1, p. 27 (2001).