Norevik, Gabriel. “Horned Grebe Podiceps Auritus and Red-Necked Grebe Podiceps Grisegena in Sweden 2011—results from a National Survey”. Ornis Svecica, vol. 24, no. 3–4, Oct. 2014, pp. 81–98, doi:10.34080/os.v24.22557.