Förschler, M. I., and O. Geiter. “Morphological Shifts in the House Sparrows Passer Domesticus of Helgoland: Insular Syndrome or Founder Effects?”. Ornis Fennica 87, no. 3 (September 30, 2010): 93–98. Accessed November 22, 2024. https://ornisfennica.journal.fi/article/view/133746.