1. Altamimi Z. Boucher C. (2001) Proceedings of the Symposium of the IAG Subcommission for Europe (EUREF) (16–18 May 2001, Dubrovnik, Croatia), The ITRS and ETRS89 relationship: new results from ITRF2000 (Mitteilungen des Bundesamtes für Kartographie and Geodasie, Band) 23, 2003.
2. Anonymous (1980) Instruction for levelling first and second order, Committee of Architecture and Public Works at the Council of Ministers, Head Office of Geodesy, Cartography and Cadastre.
3. Becker M. Zerbini S. Baker T. (2002) Assessment of height variations by GPS at Mediterranean and Black Sea coast tide gauges from SELF projects. Global and Planetary Change 34:5–35.
4. Bonchev E. (1980) in Geodynamics of the Balkans, Basic geodynamic problems of our lands, eds Nachev I. Ivanov R. (Technique, Sofia) in Bulgarian, pp 83–93.
5. On the seismicity of South-West Bulgaria during 1980–1999;Botev;Reports on Geodesy,2000