Riadh Chteoui & Anouar Ben Mabrouk. (1970). A Generalized Lyapunov-Sylvester Computational Method for Numerical Solutions of NLS Equation with Singular Potential.
            <i>Analysis in Theory and Applications</i>. <i>33</i> (4).
            333-354.
         doi:10.4208/ata.2017.v33.n4.4