Quality of SM studies:
* Fernández-de-las-Peñas C, Alonso-Blanco C, San-Roman J, Miangolarra-Page JC (2006). "Methodological quality of randomized controlled trials of spinal manipulation and mobilization in tension-type headache, migraine, and cervicogenic headache". J Orthop Sports Phys Ther 36 (3): 160–9. PMID 16596892.
* Johnston BC, da Costa BR, Devereaux PJ, Akl EA, Busse JW; Expertise-Based RCT Working Group (2008). "The use of expertise-based randomized controlled trials to assess spinal manipulation and acupuncture for low back pain: a systematic review". Spine 33 (8): 914–8. doi:10.1097/BRS.0b013e31816b4be4. PMID 18404113.
Hancock MJ, Maher CG, Latimer J, McAuley JH (2006). "Selecting an appropriate placebo for a trial of spinal manipulative therapy" (PDF). Aust J Physiother 52 (2): 135–8. PMID 16764551