Peterson, RT, G Mountfort and PAD Hollom. 1993. Collins Field Guide – Birds of Britain and Europe, 5th Revised edition. London: HarperCollins Publishers. ISBN 978-0002199001
Peterson, RT, G Mountfort and PAD Hollom. 1993. Collins Field Guide – Birds of Britain and Europe, 5th Revised edition. London: HarperCollins Publishers. ISBN 978-0002199001