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2. Extended interval arithmetic;Markov;Compt. Rend. Acad. Bulg. Sci.,1977
3. Calculus for interval functions of a real variable
4. On the Algebra of Intervals and Convex Bodies;Markov;J. Univers. Comput. Sci.,1998
5. Integration des applications measurables dont la valeur est un compact convexe;Hukuhara;Funkcialaj Ekvacioj,1967