CHALLENGES IN INTEGRATING A VIRTUAL PROJECT OFFICE: A SURVEY OF HIGH-TECH ENTERPRISES IN THE REPUBLIC OF BULGARIA. ENVIRONMENT. TECHNOLOGY. RESOURCES. Proceedings of the International Scientific and Practical Conference, [S. l.], v. 1, p. 157–164, 2025. DOI: 10.17770/etr2025vol1.8669. Disponível em: https://archive-journals.rtu.lv/etr/article/view/5007.. Acesso em: 11 mar. 2026.