1. Smith BH, Elliott AM, Chambers WA, Cairns Smith W, Hannaford PC, Penny K. The impact of chronic pain in the community. Fam Pract. 2001;18(3):292-9.
2. Breivik H, Collett B, Ventafridda V, Cohen R, Gallacher D. Survey of chronic pain in Europe: prevalence, impact on daily life, and treatment. Eur J Pain. 2006;10(4):287-333.
3. Smith BH, Elliott AM, Hannaford PC. Is chronic pain distinct diagnosis in primary care? Evidence arising from Royal College of General Practitioners' Oral Contraception study. Fam Pract. 2004;21(1):66-74.
4. Andersson HI. The course of non-malignant chronic pain: a 12-year follow-up of cohort from the general population. Eur J Pain. 2004;8(1):47-53.
5. Tsang A, von Korf M, Lee S, Alonso J, Karam E, Anger - meyer MC, et al. Common chronic pain conditions in developed and developing countries: gender and age diferences and comorbidity with depression-anxiety disorders. J Pain. 2008;9(10):883-91. doi: 10.1016/j.jpain.2008.05.005.
6. Triva P, Jukić M, Puljak L. Access to public healthcare services and waiting times for patients with chronic nonmalignant pain: feedback from a tertiary pain clinic. Acta Clin Croat. 2013;52(1):79-85.
7. Leverence RR, Williams RL, Potter M, Fernald D, Unverzagt M, Pace W, et al. Chronic non-cancer pain: aA siren for primary care - a report from the PRImary care MultiEthnic Network (PRIME Net). J Am Board Fam Med. 2011;24(5):551-61. doi: 10.3122/jabfm.2011.05.110030.
8. Clark LH, Upshur CC. Family medicine physicians' views of how to improve chronic pain management. J Am Board Fam Med. 2007;20:479-82.
9. Boulanger A, Clark AJ, Squire P, Cui E, Horbay GLA. Chronic pain in Canada: have we improved our management of chronic noncancer pain? Pain Res Manage. 2007;12(1):39- 47.
10. Elliot AM, Smith BH, Hannaford PC, Smith WC, Chambers WA. The course of chronic pain in the community: re - sults of 4-year follow-up study. Pain. 2002;99(1-2):299-307.
11. Breivik H, Borchgrevink PC, Allen SM, Rosseland LA, Romundstad L, Breivik Hals EK, et al. Assessment of pain. Br J Anaesth. 2008;101(1):17-24. doi: 10.1093/bja/aen103
12. Dworkin RH, Turk DC, Wyrwich KW, Beaton D, Cleeland CS, Farrar JT, et al. Interpreting the clinical importance of treatment outcomes in chronic pain clinical trials. IMMPACT recommendation. J Pain. 2008;9:105-21. [OpenAIRE]
13. Smith MT, Haythornthwaite JA. How do sleep disturbance and chronic pain inter-relate? Insights from the longitudinal and cognitive behavioural clinical trials literature. Sleep Med Rev. 2004;8(2):119-32.
14. Goral A, Lipsitz JD, Gross R. The relationship of chronic pain without comorbid psychiatric disorder to sleep disturbance and health care utilisation: results from the Israel National Health Survey. J Psychosom Res. 2010; 69:44-57. doi: 10.1016/j.jpsychores.2010.05.012.
15. Cole JC, Dubois D, Kosinski M. Use of patient-reported sleep measures in clinical trials of pain treatment: a literature review and synthesis of current sleep measures and conceptual model of sleep disturbance in pain. Clin Ther. 2007;29:2580- 8.