Baranovich, A.M. and Daletskii, Y.L. (1996) “Differential-geometric relations for a class of formal operator power series”, Methods of Functional Analysis and Topology, 2(1), pp. 1–16. Available at: https://zen.imath.kiev.ua/index.php/mfat/article/view/6 (Accessed: 19 December 2025).