The equation $ - \varDelta u = f(x, u)$ on $\Bbb R^N$ as a general equation of the Emden-Fowler type is considered. Under appropriate conditions, positive and multiple solutions are obtained.
S. B. Tshinanga. "Positive and multiple solutions of subcritical Emden-Fowler equations." Differential Integral Equations 9 (2) 363 - 370, 1996. https://doi.org/10.57262/die/1367603352