1. “Sur la theorie des equations non-lineaires aux derivees partielles,”Comptes Rendus, 1936,203, 1120.
2. See my paper “On the Theory of Non-Linear Partial Differential Equations of the Parabolic Type,”Jour. Ind. Math. Soc., 1939,3.
3. “On an Infinite System of Non-linear Integral Equations,”Proc. Ind. Acad. Sci., 1938,8, 238.
4. Courant, R., und Hilbert, D.,Methoden Der Mathematischen Physik, Erster 2nd Ed., p. 251.
5. Ince,Ordinary Differential Equations, p. 270.