1. Bhatia, R.: Matrix Analysis, Graduate Texts in Mathematics 169. Springer, New York (1997)
2. Choi, M.D.: Positive linear maps on C*-algebras. Can. J. Math. 24, 520–529 (1972)
3. Choi, M.D.: A Schwarz inequality for positive linear maps on C*-algebras. Ill. J. Math. 18, 565–574 (1974)
4. Choi, M.D.: Completely positive linear maps on complex matrices. Linear Algebra Appl. 10, 285–290 (1975)
5. Choi, M.D.: Some assorted inequalities for positive linear maps on C*-algebras. J. Oper. Theory 4, 271–285 (1980)