1. La Montagna G, Tirri R, Baruffo A, Preto B, Viaggi S: Clinical pattern of pain in rheumatoid arthritis. Clin Exp Rheum. 1997, 15: 481-485.
2. Kazis LE, Meenan RF, Anderson JJ: Pain in the rheumatic disease. Arthritis Rheum. 1983, 26: 1017-1022.
3. Bird HA, Dixon JS: The measurement of pain. Baillieres Clin Rheumatol. 1987, 1: 71-89.
4. Grossi E, Borghi C, Cerchiari EL, Della Puppa T, Francucci B: Analogue chromatic continuous scale (ACCS): a new method for pain assessment. Clin Exp Rheumatol. 1983, 1: 337-340.
5. Melzack R: The McGill Pain questionnaire: major properties and scoring methods. Pain. 1985, 21: 85-92.