On a mean value theorem, and its converse, for the displacements in the theory of elasticity Diaz, J.B.; Payne, L.E. — 1958 Portugaliae mathematica
Reflection principles for Laplace's equation when the boundary data involves derivatives of higher order Diaz, J.B.; Ram, R.B.; Verma, G.R. Portugaliae mathematica
Complementary Inequalities. III. Inequalities Complementary to Schwarz's Inequality in Hilbert Space. J.B. DIAZ; F.T. METCALF Mathematische Annalen