RT Journal Article SR Electronic T1 Subgroups within "nonspecific" low back pain. JF The Journal of Rheumatology JO J Rheumatol FD The Journal of Rheumatology SP 395 OP 396 VO 32 IS 3 A1 Gordon Waddell YR 2005 UL http://www.jrheum.org/content/32/3/395.abstract AB