@misc{sparks_are_european_1999, 
author={Sparks, T.,Heyen, H.,Braslavska, O.,Lehikoinen, E.},
title={Are European birds migrating earlier?},
year={1999},
howpublished = {journal article},
note = {Online available at: \url{} (DOI). Sparks, T.; Heyen, H.; Braslavska, O.; Lehikoinen, E.: Are European birds migrating earlier?. BTO News (British Trust for Ornithology). 1999. vol. 223, 8-9.}}