Mohammad Javad Habibi Vosta Kolaei & Shahroud Azami. (2021). Geometric Estimates of the First Eigenvalue of $(p,q)$-Elliptic Quasilinear System Under Integral Curvature Condition.
            <i>Journal of Partial Differential Equations</i>. <i>34</i> (4).
            348-368.
         doi:10.4208/jpde.v34.n4.3