D. O. Muñoz-Ramírez, V. Ponomaryov, R. Reyes-Reyes, C. Cruz-Ramos, and S. N. Sadovnychiy, “Embedding a Color Watermark into DC coefficients of DCT from Digital Images”, IEEE LAT AM T, vol. 17, no. 8, pp. 1326–1334, Dec. 2019.