Salaffi, F., A. Stancati, R. Procaccini, F. Cioni, and W. Grassi. “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 57, no. 4 (1): 238-249. Accessed September 20, 2020. https://www.reumatismo.org/index.php/reuma/article/view/reumatismo.2005.238.