1. Andreeva, M. (n.d.). Innovation in the public sector [Андреева, М. (n.d.). Иновации в публичния сектор]. Available at https://www.ipa.government.bg/sites/default/files/innovation_overall_mandreeva.pdf (24.06.06).
2. Angelov, G. (2020). Where are eServices in Bulgaria? DW. [Ангелов, Г. (2020). Милиони на вятъра: Къде са електронните услуги в България? DW].
3. Aydin, O. (Ed.). (2020). The impact of digital transformation. Efe Akademi.
4. Damanpour, F., Walker, R. M., & Avellaneda, C. N. (2009). Combinative effects of innovation types and organizational performance: A longitudinal study of service organizations. Journal of Management Studies, 46(4), 650–675.
5. Dervishaj, V. (2023). Embracing innovation in public administration: A data driven imperative. Available at https://www.cef-see.org/blog/embracing-innovation-in-public-administration-a-data-driven-imperative (24.06.06).