On the differential equation \[ \sum A_{ik}(x,y)\frac{\partial^{i+k}z}{\partial x^i\partial y^k} = 0,\left(\begin{aligned} i &=0,1,\dots, p,\\ k &= 0,1,\dots,q,\end{aligned} p+q=n,\,A_{pq}=1\right). \]

This page was built for publication: On the differential equation \[ \sum A_{ik}(x,y)\frac{\partial^{i+k}z}{\partial x^i\partial y^k} = 0,\left(\begin{aligned} i &=0,1,\dots, p,\\ k &= 0,1,\dots,q,\end{aligned} p+q=n,\,A_{pq}=1\right). \]