\[
\boxed{
{\it f0} \left( x \right) y \left( x \right) {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left( x \right) +{\it f1} \left( x \right)  \left( {\frac {\rm d}{{\rm d}x}}y \left( x \right)  \right) ^{2}+{\it f2} \left( x \right) y \left( x \right) {\frac {\rm d}{{\rm d}x}}y \left( x \right) +{\it f3} \left( x \right)  \left( y \left( x \right)  \right) ^{2}=0}
\]