National Health Service: Common posture mistakes and fixes. nhs.uk/Livewell/Backpain/Pages/back-pain-and-common-posture-mistakes.aspx.
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Mayo Clinic. Speaking of Health: Better posture. 3 tips for standing up straight. mayoclinichealthsystem.org/hometown-health/speaking-of-health/better-posture-3-tips-for-standing-up-straight.