Gurzău, Mircea Octavian. “The Convexity of Interval-Functions”.
Anal. Numér. Théor. Approx.
5, no. 1 (February 1, 1976): 23–26. Accessed April 11, 2025.
https://ictp.acad.ro/jnaat/journal/article/view/1976-vol5-no1-art2
.