Díaz Díaz, Roberto Adolfo, et al. “Analysis of International Trade of the Department of Tolima: Application of the Gravity Model in the Period 2009-2019”. Challenges and Trends for the Sustainability of Organizations in Scenarios of Uncertainty, Sello Editorial UNAD, 2022, pp. 224-47, https://doi.org/10.22490/9789586518352.10.