M. A. Gómez Muñoz, L. M. Chalapud-Nárvaez, and C. A. Lasso-Quilindo, “Effects of concurrent training on physical fitness parameters and specific performance in young swimmers competing in 50 and 100 meter freestyle events”, Retos, vol. 71, pp. 302–315, Aug. 2025, doi: 10.47197/retos.v71.111939.