Doukas, I. D., Ampatzidis, D., & Kampouris, V. (2017). THE VALIDATION OF THE TRANSFORMATION BETWEEN AN OLD GEODETIC REFERENCE FRAME AND A MODERN REFERENCE FRAME, BY USING EXTERNAL SPACE TECHNIQUES SITES: THE CASE STUDY OF THE HELLENIC GEODETIC REFERENCE SYSTEM OF 1987. Boletim De Ciências Geodésicas, 23(3). Recuperado de https://revistas.ufpr.br/bcg/article/view/55432