HU, S.; WU, F.; WU, L. Impact of COVID-19 on the Big Industrial Enterprises in Hebei, China: Grey Forecast Perspective. International Journal of Grey Systems, [S. l.], v. 2, n. 2, p. 13–17, 2022. DOI: 10.52812/ijgs.60. Disponível em: https://publish.thescienceinsight.com/index.php/ijgs/article/view/60. Acesso em: 4 apr. 2025.