NESSET, Tore. Opaque Softening: A Usage-Based Approach. Poljarnyj vestnik, Tromsø, Norway, v. 8, p. 55–68, 2005. DOI: 10.7557/6.1331. Disponível em: https://septentrio.uit.no/index.php/vestnik/article/view/1331. Acesso em: 9 jun. 2026.