WÓJCIK, Paweł. A simple proof of the Polar Decomposition Theorem. Annales Mathematicae Silesianae, [S. l.], v. 31, p. 165–171, 2016. Disponível em: https://trrest.vot.pl/ojsus/index.php/AMSIL/article/view/13948. Acesso em: 7 may. 2025.