Dzуadуk V.K. (1971) “On one method to construct normal in A. N. Tikhonov’s sense of linear equations”, Ukrains’kyi Matematychnyi Zhurnal, 23(2), pp. 235–239. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/8506 (Accessed: 7 April 2025).