INYANG, E. P., I. O. Akpan, E. P. Inyang, and E. S. William. “Approximate Solutions of the Schrödinger Equation With Hulthén-Hellmann Potentials for a Quarkonium System”. Revista Mexicana De Física, vol. 67, no. 3 May-Jun, May 2021, pp. 482–490, doi:10.31349/RevMexFis.67.482.