Veistola, S., E. Lehikoinen, and T. Eeva. “Weather and Breeding Success at High Latitudes-the Pied Flycatcher Ficedula Hypoleuca and the Siberian Tit Parus Cinctus”. Ornis Fennica, vol. 74, no. 2, July 1997, pp. 89–98, https://ornisfennica.journal.fi/article/view/133461.