E. Ribeiro et al., "A study on dialog act recognition using character-level tokenization", in 18th Int. Conf. on Artificial Intelligence: Methodology, Systems, and Applications, AIMSA 2018, Gennady Agre, Josef van Genabith, Thierry Declerck, Ed., Varna, Springer, 2018, vol. 11089, pp. 93-103