Gavrea, I., and M. Ivan. “Sur Une Inegalité De Levinson-Popoviciu: On a Levinson-Popoviciu Inequality”. Anal. Numér. Théor. Approx. 11, no. 1 (August 1, 1982): 75–79. Accessed April 17, 2025. https://ictp.acad.ro/jnaat/journal/article/view/1982-vol11-nos1-2-art9.