1. National Museum of Natural SciencesSpanish Research Council (CSIC) Calle de Serrano 115 bis 28006 Madrid Spain
2. National Distance Education University (UNED) Calle de Bravo Murillo 38 28015 Madrid Spain
3. Department of Geography and GeologyUniversity of Turku Turku 20014 Turun yliopisto Finland
4. Finnish Geodetic Research Institute FGI Geodeetinrinne 2 FI-02430 Masala Finland