Weedbrook, C.; Pirandola, S.; García-Patrón, R.; Cerf, N. J.; Ralph, T. C.; Shapiro, J. H.; Lloyd, S. Gaussian quantum information. Reviews of Modern Physics. 2012, 84 (2): 621. doi:10.1103/RevModPhys.84.621(英语).
Pechukas, P. Reduced dynamics need not be completely positive. Physical review letters. 1994, 73 (8): 1060. doi:10.1103/PhysRevLett.73.1060.
Shaji, A.; Sudarshan, E. C. G. Who's afraid of not completely positive maps?. Physics Letters A. 2005, 341 (1): 48–54. doi:10.1016/j.physleta.2005.04.029(英语).