Sauchelli S, Bradley J, Cox J, England C, Perry R. Weight maintenance interventions for people with type 2 diabetes mellitus: a systematic review protocol. Syst Rev. 2020 Sep 12;9(1):210. doi: 10.1186/s13643-020-01467-7
Demeyin (Nuabor) WA, Frost J, Ukoumunne OC, Briscoe S, Britten N. N of 1 trials and the optimal individualisation of drug treatments: a systematic review protocol. Syst Rev. 2017 Apr 24;6(1):90. doi: 10.1186/s13643-017-0479-6
Luciano JV, Barrada JR, Aguado J, Osma J, García-Campayo J. Bifactor analysis and construct validity of the HADS: a cross-sectional and longitudinal study in fibromyalgia patients. Psychological Assessment. 2014 Jun;26(2):395-406.