PT - JOURNAL ARTICLE ED - BMJ Publishing Group Ltd TI - Medium firm mattresses reduced pain related disability more than firm mattresses in chronic, non-specific low back pain AID - 10.1136/ebm.9.4.119 DP - 2004 Jul 01 TA - Evidence Based Medicine PG - 119--119 VI - 9 IP - 4 4099 - http://ebm.bmj.com/content/9/4/119.short 4100 - http://ebm.bmj.com/content/9/4/119.full SO - Evid Based Med2004 Jul 01; 9