Jivall, Lotti, Jānis Kaminskis, and Eimuntas Paršeliūnas. 2012. “Improvement and Extension of ETRS 89 in Latvia and Lithuania Based on the NKG 2003 GPS Campaign”. Geodesy and Cartography 33 (1):13-20. https://doi.org/10.3846/13921541.2007.9636710.