Representativeness of point-wise phenological Betula data collected in different parts of Europe. - Siljamo, P.; Sofiev, M.; Ranta, H.; Linkosalo, T.; Kubin, E.; Ahas, R.; Genikhovich, E.; Jatczak, K.; Jato, V.; Nekovar, J.; Minin, A.; Severova, E.; et al. (UK, 2008)