Question of civilization in circular theory Applications about Ibn Khaldun, Oswald Spengler and Arnold Toynbee. Journal of Social Sciences, [S. l.], v. 2, n. 07, p. 53–64, 2018. Disponível em: https://journalsocialsciences.de/index.php/jss/article/view/601. Acesso em: 4 aug. 2026.