Kátai, I. ., K. B, and P. B. “ON THE EQUATION F(n² + M² + K) = H(n) + H(m) + K”. Thang Long Journal of Science: Mathematics and Mathematical Sciences, vol. 1, no. 4, Feb. 2023, pp. 135-51, https://science.thanglong.edu.vn/index.php/volc/article/view/54.