Grypeos, M. E., and T. E. Liolios. “Approximate Determination of the Ground-State Schroedinger Eigenfunction by Means of the Hypervirial Theorems Technique”. HNPS Advances in Nuclear Physics 7 (December 5, 2019): 56–62. Accessed May 2, 2024. https://eproceedings.epublishing.ekt.gr/index.php/hnps/article/view/2397.