Otterbeck, A., Dale, S., Lindén, A. and Marthinsen, G. (2013) “A male Reed Warbler and Marsh Warbler hybrid (Acrocephalus scirpaceus × A. palustris) in Norway documented with molecular methods”, Ornis Norvegica, 36, pp. 6–13. doi: 10.15845/on.v36i0.351.