VOERKEL, Paul; ZHONG, Xingyu. German language teaching and sustainability – approaching theory and practice. Journal for German and Scandinavian Studies / Списание „Германистика и скандинавистика“, [S. l.], v. 1, p. 364–389, 2025. Disponível em: https://periodicals.uni-sofia.bg/index.php/gsc/article/view/3229. Acesso em: 9 feb. 2026.