1. Partial Differential Equations and Continuum Mechanics;Kampéde Fériet,1961
2. Sur une classe de fonctions u(x, y, t) harmoniques en (x, y) et satisfaisant l'équation de la chaleur en (x, t);Widder;Comp. Rend.,1963
3. Functions of three variables which satisfy both the heat equation and Laplace's equation in two variables;Widder;J. Austral. Math. Soc.,1963
4. The Laplace Transform;Widder,1941
5. Positive solutions of the heat equation;Widder;Bull. Am. Math. Soc.,1963