Rassias Themistocles M Rassias 
Constantin Caratheodory: An International Tribute (In 2 Volumes) [PDF ebook] 

The object of these 2 volumes of collected papers is to provide insight and perspective on various research problems and theories in modern topics of Calculus of Variations, Complex Analysis, Real Analysis, Differential Equations, Geometry and their Applications, related to the work of Constantin Caratheodory. This work will be of interest both to researchers following the development of new results, and to people seeking an introduction in these fields.