Syrovatskyi, V.N. 2013. Functional models of commutative systems of operators close to the unitary. Visnyk of V. N. Karazin Kharkiv National University. Ser. Mathematics, Applied Mathematics and Mechanics. 1081 (Dec. 2013), 54-66. DOI:https://doi.org/10.26565/2221-5646-2013-1081-06.