Não informado. (1971). Birds in Northumbria: Northumberland bird report. Tyneside Bird Club.
Style de citation Chicago (17e éd.)Não informado. Birds in Northumbria: Northumberland Bird Report. Newcastle upon Tyne, Inglaterra: Tyneside Bird Club, 1971.
Style de citation MLA (8e éd.)Não informado. Birds in Northumbria: Northumberland Bird Report. Tyneside Bird Club, 1971.
Attention : ces citations peuvent ne pas être correctes à 100%.