Dill, William A.: Inland Fisheries of Europe, s. 80–87. European Inland Fisheries Advisor and Commission Technical Papers 52, ISSN 0532-940X. Food and Agriculture Organization of the United Nations, 1993. ISBN 9251033587. Teoksen verkkoversio.
McColl, R. W. (toim.): Encyclopedia of World Geography, s. 4–5. Nide 1. Facts on File Library of World Geography. Infobase Publishing, 2014. ISBN 0816072299. Teoksen verkkoversio.