ZAHARIEV, Svetlozar Kirilov. Validation and Optimisation of Common Clear Sky Models with a use case for North-East Bulgaria. ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, [S. l.], v. 5, n. 1, p. 1–12, 2021. DOI: 10.29114/ajtuv.vol5.iss1.224. Disponível em: https://aj.tu-varna.bg/index.php/ajtuv/article/view/224. Acesso em: 2 oct. 2025.