Pragmatic methods for reviewing exceptionally large bodies of evidence: systematic mapping review and overview of systematic reviews using lung cancer survival as an exemplar oleh Ruth Lewis, Maggie Hendry, Nafees Din, Marian A. Stanciu, Sadia Nafees, Annie Hendry, Zhi Hao Teoh, Thomas Lloyd, Rachel Parsonage, Richard D. Neal, Gareth Collier, Dyfed W. Huws