Altomare, Francesco, and Vita Leonessa. “Continuous Selections of Borel Measures, Positive Operators and Degenerate Evolution Problems”. Rev. Anal. Numér. Théor. Approx. 36, no. 1 (February 1, 2007): 9–23. Accessed May 17, 2024. https://ictp.acad.ro/jnaat/journal/article/view/2007-vol36-no1-art2.