M. G. A. A. Siregar, Said Iskandar Al Idrus, Hermawan Syahputra, Insan Taufik, and Kana Saputra S, “Classification of Purple Passion Fruit Ripeness Levels Using Convolutional Neural Network (CNN)”, j. of artif. intell. and eng. appl., vol. 5, no. 2, pp. 2152–2159, Feb. 2026.