1. Extensions of linear transformations in Hilbert space which extend beyond this space;Sz-Nagy,1960
2. Dissipative operators and hyperbolic systems of partial differential equations;Phillips;Trans. Amer. Math. Soc.,1959
3. Introduction to the geometry of indefinite J-spaces and to the theory of operators in those spaces;Krein;Amer. Math. Soc. Transl.,1970
4. On J-contractive operator functions;Ginzburg;Pokl. Akad. Nauk SSSR,1957