Key Performance Indicators(PDF). The British Library Annual Report and Accounts 2010/11. British Library: 31. 2010-11 [2020-04-09]. (原始内容(PDF)存档于2016-12-24) (英语).
Key Performance Indicators(PDF). The British Library Annual Report and Accounts 2010/11. British Library: 31. 2010-11 [2020-04-09]. (原始内容(PDF)存档于2016-12-24) (英语).