Fréchet-Legendre Functions and Reflexive Banach Spaces
Jonathan M. Borwein, Jon Vanderwerff
H. H. Bauschke, J. M. Borwein and P. L. Combettes ["Essential smoothness, essential strict convexity, and Legendre functions in Banach spaces", Communications in Contemp. Mathematics 3 (2001) 615–647] showed how to extend naturally the classical definitions of essential smoothness and essential strict convexity from functions on