Słowik, R. “The Drazin Inverses of Infinite Triangular Matrices and Their Linear Preservers”.
Ukrains’kyi Matematychnyi Zhurnal
, vol. 70, no. 4, Apr. 2018, pp. 534-48,
https://umj.imath.kiev.ua/index.php/umj/article/view/1574
.