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.
Bradley RH, National Institute of Child Health and Human Development (NICHD) Early Child Care Research Network, McLeod LD. Child care and common communicable illnesses in children aged 37 to 54 months. Arch Pediatr Adolesc. 2003 Feb;157(2):196-200. doi: 10.1001/archpedi.157.2.196