1. Adamjan, V.M., Arov, D.Z., Kreĭn, M.G.: Analytic properties of the Schmidt pairs of a Hankel operator and the generalized Schur-Takagi problem. Mat. Sb. (N.S.) 86(128), 34–75 (1971)
2. Adamjan, V.M., Arov, D.Z., Kreĭn, M.G.: Infinite Hankel block matrices and related problems of extension. Izv. Akad. Nauk Armjan. SSR Ser. Mat. 6(2–3), 87–112 (1971)
3. Adamjan, V.M., Arov, D.Z., Kreĭn, M.G.: Infinite Hankel block matrices and related extension problems. Am. Math. Soc. Transl. 111(133), 133–156 (1978)
4. Ahlfors, L.V.: Complex Analysis. An Introduction to the Theory of Analytic Functions of One Complex Variable. McGraw-Hill, New York/Toronto/London (1953)
5. Akaike, H.: A new look at the statistical model identification. IEEE Trans. Autom. Control 19, 716–722 (1974)