M. Esteban-Blanco, et al. “Protective Effect of Mesenchymal Stem Cells Derived Secretome in an in Vitro Pro-Inflammatory Model of Intervertebral Discogenic Pain”. Global Journal of Medical Research, vol. 21, no. G1, Jan. 2021, pp. 31-41, https://medicalresearchjournal.org/index.php/GJMR/article/view/2486.