1. Adamjan, V.M., Arov, D.Z.: On unitary coupling of semiunitary operators. Dokl. Akad. Nauk. Arm. SSR XLIII(5), 257–263 (1966);
2. English translation: Am. Math. Soc. Transl. 95, 75–129 (1970)
3. Adamjan, V.M., Arov, D.Z., Kreĭn, M.G.: Infinite Hankel matrices and generalized problems of Carathéodory–Fejér and I. Schur. Funkcional. Anal. Prilozhen. 2(4), 1–17 (1968);
4. English translation: Funct. Anal. Appl. 2(2), 269–281 (1968)
5. Adamjan, V.M., Arov, D.Z., Kreĭn, M.G.: Infinite Hankel block matrices and related extension problems. Izv. Akad. Nauk Armjan. SSR Ser. Mat. 6, 87–112 (1971);