KIEFER, Claus. Does time exist in quantum gravity?. Philosophical Problems in Science (Zagadnienia Filozoficzne w Nauce), [S. l.], n. 59, p. 7–24, 2015. DOI: 10.59203/zfn.59.180. Disponível em: https://www.zfn.edu.pl/index.php/zfn/article/view/180. Acesso em: 26 nov. 2025.