Pfau, C.; Bartha, Éva; Bácsné Bába , Éva; Szabóné Szőke, R.; Müller, A. Survey of the Service Offer of Fitness Clubs for Group Classes in Debrecen . IJEMS 2021, 6 (2), 35-48. https://doi.org/10.21791/IJEMS.2021.2.4..