On Roots and Logarithms of Elements of a Complex Banach Algebra. E. Hille — 1958 Mathematische Annalen
Some Properties of the Jordan Operators. (Short Communication). E. Hille — 1968 Aequationes mathematicae
Remarks on transfinite diameters Hille, E. — 1962 General Topology and its Relations to Modern Analysis and Algebra