Bishop, Annette, Wynne-Jones, Gwenllian, Lawton, Sarah A, van der Windt, Danielle, Main, Chris, Sowden, Gail, Burton, A Kim, Lewis, Martyn, Jowett, Sue, Sanders, Tom, Hay, Elaine M, Foster, Nadine E, "Rationale, design and methods of the Study of Work and Pain (SWAP): a cluster randomised controlled trial testing the addition of a vocational advice service to best current primary care for patients with musculoskeletal pain (ISRCTN 52269669)", BMC Musculoskeletal Disorders, 2014