Sirovatsky, V.N. 2012. 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. 1018 (Apr. 2012), 41-61. DOI:https://doi.org/10.26565/2221-5646-2012-1018-04.