1.
Elhousseyn B, Abbas B. The role of research and development in increasing the competitive performance of petroleum companies: A case study of Royal Dutch Shell PLC. Int. tax j. [Internet]. 2025 Oct. 14 [cited 2026 Apr. 19];52(5):2545-56. Available from: https://internationaltaxjournal.online/index.php/itj/article/view/264