1. D.R. Farenick, C*-convexity and matricial ranges, Canad. J. Math., to appear.
2. Über den numerischen Wertebereich eines Operators;Hildebrandt;Math. Ann.,1966
3. C∗-extreme points;Hopenwasser;Trans. Amer. Math. Soc.,1981
4. Some remarks on C∗-convexity;Loebl;Linear Algebra Appl.,1981
5. Numerical range and norm;Nakamura;Math. Japon,1982