Salaffi, F., et al. “Assessment of Circadian Rhythm in Pain and Stiffness in Rheumatic Diseases According the EMA (Ecologic Momentary Assessment) Method: Patient Compliance With an Electronic Diary”. Reumatismo, vol. 57, no. 4, Dec. 2005, pp. 238-49, doi:10.4081/reumatismo.2005.238.