Reference

Miriam Liedvogel, Keith W. Larson, Max Lundberg, Arzu Gursoy, Leonard I. Wassenaar, Keith A. Hobson, Staffan Bensch, Susanne Akesson (2014): No evidence for assortative mating within a willow warbler migratory divide – Frontiers in Zoology – 2014: 0001-52-0009.