Hedenström A, Pettersson J. Migration routes and wintering areas of Willow Warblers Phylloscopus trochilus (L.) ringed in Fennoscandia. Ornis Fenn [Internet]. 1987Dec.31 [cited 2024Nov.22];64(4):137–143. Available from: https://ornisfennica.journal.fi/article/view/133244