Ruiz-Olmo, J., Loy, A., Cianfrani, C., Yoxon, P., Yoxon, G., de Silva, P.K., Roos, A., Bisther, M., Hajkova, P. & Zemanova, B. (2008). Lutra lutra. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 21 наурыз 2009. Database entry includes justification for why this species is near threatened
