Biolcheva P, Vasil Bozev. The Progress of Industry 4.0 in the Conditions of a Pandemic - Bulgarian Case in Natural Gas Sector. jstard [Internet]. 2022 Jun. 21 [cited 2024 Jul. 1];4(1):1-8. Available from: https://publisher.uthm.edu.my/ojs/index.php/jstard/article/view/11349