F. R. Chan, Firdaus Annas, Yulifda Elin Yuspita, and Gusnita Darmawati, “Implementation of Convolutional Neural Networks (CNN) in An Emotion Detection System for Measuring Learning Concentration Levels”, Knowbase: Int. J. Knowl. Database, vol. 4, no. 1, pp. 49–61, Aug. 2024.