1. M. Sh. Birman and M. Z. Solomyak, in Problems of Mathematical Physics, issue 1 (Izd. Leningrad. Gos. Univ., Leningrad, 1966), pp. 33–67 [in Russian].
2. M. Sh. Birman and M. Z. Solomyak, in Problems of Mathematical Physics, issue 2 (Izd. Leningrad. Gos. Univ., Leningrad, 1967), pp. 26–60 [in Russian].
3. F. A. Berezin, Method of Second Quantization, 2nd ed. (Nauka, Moscow, 1986) [in Russian].
4. I. Ts. Gokhberg and M. G. Krein, Introduction to the Theory of Linear Non-Self-Adjoint Operators in Hilbert Space (Nauka, Moscow, 1965) [in Russian].
5. J. J. Koliha and V. Rakočević, Integral Equations Operator Theory 52(1), 125 (2005).