The effect of financial leverage on the profitability of economic services companies - Case study of the Sonelgaz company in Guelma for the period )2017-2019(. Alijtihed [Internet]. 2023 Jan. 31 [cited 2025 Jul. 30];12(01):504-23. Available from: https://alijtihed.univ-tam.dz/article/view/140