1. N. Azamov, A. Carey, P. Dodds, F. Sukochev, Operator integrals, spectral shift, and spectral flow. Canad. J. Math. 61(2), 241–263 (2009). MR 2504014
2. R. Bhatia, Matrix Analysis. Graduate Texts in Mathematics (Springer, New York, 1996)
3. M. Birman, M. Solomyak, Double Stieltjes Operator Integrals. I. Problems of Mathematical Physics, No. 1, Spectral Theory, Diffraction Problems (Russian) (Izdat. Leningrad. University, Leningrad, 1966), pp. 33–67
4. M. Birman, M. Solomyak, Double Stieltjes Operator Integrals. II. Problems of Mathematical Physics, No. 2, Spectral Theory, Diffraction Problems (Russian) (Izdat. Leningrad. University, Leningrad, 1967), pp. 26–60. MR 0234304
5. M. Birman, M. Solomyak, Double Stieltjes Operator Integrals. III. Problems of Mathematical Physics, No. 6 (Russian) (Izdat. Leningrad. University, Leningrad, 1973), pp. 27–53. MR 0348494