[4] Varadarajan V. S.: 
Probability in physics and a theoгem on simultaneous observability. Comm. Pure Appl. Math. 15 (1962), 189-217. 
MR 0163616 
[5] Varadarajan V. S.: 
Geometгy of Quantum Theory, vol. I. D. van Nostrand Comp., Inc, 1968. 
MR 0471674