Olsson, O., and J. Hentati-Sundberg. “Population Trends and Status of Four Seabird Species (Uria Aalge, Alca Torda, Larus Fuscus, Larus Argentatus) at Stora Karlsö in the Baltic Sea”. Ornis Svecica, vol. 27, no. 2–4, Oct. 2017, pp. 64–93, doi:10.34080/os.v27.19558.