Corovei, I. “Some Functional Equations Connected With Quadratic Forms”. Anal. Numér. Théor. Approx. 19, no. 2 (August 1, 1990): 123–127. Accessed April 11, 2025. https://ictp.acad.ro/jnaat/journal/article/view/1990-vol19-no2-art4.