Wang, X., Y. Yang, Y. Deng, and K. He. “Adversarial Training With Fast Gradient Projection Method Against Synonym Substitution Based Text Attacks”. Proceedings of the AAAI Conference on Artificial Intelligence, vol. 35, no. 16, May 2021, pp. 13997-05, doi:10.1609/aaai.v35i16.17648.