*[http://www.hbw.com/lynx/en/lynx-edicions/monografias-naturaleza/MON0009-ecology-conservation-steppe-land-birds.html ''Ecology and Conservation of Steppe-land Birds''] by Manuel B.Morales, Santi Mañosa, Jordi Camprodón, Gerard Bota. International Symposium on Ecology and Conservation of steppe-land birds. Lleida, Spain. December 2004.ISBN 84-87334-99-7