Includes bibliographical references.

functions -- analytic functions mapping the upper halfplane into itself /; On the spectral functions of the string /; �Ceby�sev-Markov inequalities in the theory of the spectral functions of the vibrating string /; On linear-fractional transformations with operator coefficients /; Divisors and minorants of operator-functions of bounded form /; A certain class of operator-valued entire functions /; The spectrum of one-dimensional singular integral operators with piecewise continuous coefficients /; The reduction method for operators in Hilbert space /; A note on the multistage method / I. S. Kac and M. G. Krein; I. S. Kac and M. G. Krein; M. G. Krein; M. G. Krein and Ju. L. Smuljan; Ju. P. Ginzburg; M. S. Brodskii; I. C. Gohberg and N. Ja. Krupnik; A. S. Markus; A. S. Markus