Acceptance and Commitment group Therapy for patients with multiple functional somatic syndromes: a three-armed trial comparing ACT in a brief and extended version with enhanced care - CORRIGENDUM. Issue 16 (11th September 2018) - Pedersen, Heidi Frølund; Agger, Johanne L.; Frostholm, Lisbeth; Jensen, Jens S.; Ørnbøl, Eva; Fink, Per; Schröder, Andreas