1] dr Milko Yovchev MEASUREMENT AND ANALYSIS OF THE SPECTRAL EMISSION OF DIFFERENT TYPES OF DOMESTIC LAMPS IN THE BLUE LIGHT HAZARD WAVELENGTH RANGE" - Contemporary Materials 2023 - Savremeni materijali, 31.07.2023.
(https://ekonferencije.com/sr1/rad/measurement-and-analysis-of-th/6508)

2] dr Milko Yovchev Technical and Economic Development of the Photovoltaic Electricity in Bulgaria" - Contemporary Materials 2019 - Savremeni Materijali, 30.06.2019.
(https://ekonferencije.com/sr1/rad/technical-and-economic-develop/5723)