Sylwester Zawadzki, "Państwo dobrobytu". Doktryna i praktyka ["The Welfare State."Doctrine and Practice], Warszawa 1964, PWN. Contemporary Central & East European Law, [S. l.], n. 4, p. 42–43, 1965. Disponível em: https://czasopisma.inp.pan.pl/index.php/cceel/article/view/1701. Acesso em: 6 oct. 2025.