Advancement of artificial intelligence techniques based lexicon emotion analysis for vaccine of COVID-19 . Periodicals of Engineering and Natural Sciences, [S. l.], v. 9, n. 4, p. 580–588, 2021. DOI: 10.21533/pen.v9.i4.968. Disponível em: https://pen.ius.edu.ba/index.php/pen/article/view/968. Acesso em: 18 apr. 2026.