1. R. Jajte and A. Paszkiewicz, “Vector Measures on the Closed Subspaces of a Hilbert Space,” Studia Math. 63, 229–251 (1978).
2. T. Ya. Azizov and I. S. Iokhvidov, The Foundations of the Theory of Linear Operators in Spaces with Indefinite Metric (Nauka, Moscow, 1986) [in Russian].
3. M. S. Matvejchuk and A. M. Ionova, “Vector Measure on the Logic of J-Projections of a Krein Space,” Int. J. Theor. Phys. 44(12), 2193–2200 (2005).
4. M. S. Matvejchuk, “A Measure on the Quantum Logic of Subspaces of a J-Space,” Sib. Matem. Zhurn. 32 101–112 (1987).
5. K. Ylinen, “The Structure of Bounded Bilinear Form on Products of C*-Algebras,” Proc. Amer. Math. Soc. 102(3), 599–602 (1988).