Subsequently, a novel integral equation formulation for the scattering of plane waves by a diffraction grating is derived using a Brakhage/Werner type ansatz for the solution. Employing the Fredholm ...

J. Reid, Estimate on Moments of the Solutions to Stochastic Differential Equations in the Plane, The Annals of Probability, Vol. 11, No. 3 (Aug., 1983), pp. 656-668 ...

These higher-degree equations are much more difficult, of course; but part of the reason solutions didn't come easily was that algebra was tied to words and concrete images for such a very long time.