1. American Pain Society. Pain: Current understanding of assessment, management and treatments. American Pain Society and National Pharmaceutical Council. www.npcnow.org/system/files/research/download/Pain-Current-Understanding-of-Assessment-Management-and-Treatments.pdf.
2. International Association for the Study of Pain. IASP Taxonomy. www.iasp-pain.org/Taxonomy?navItemNumber=576.
3. WHO. Treatment guidelines on pain. www.who.int/medicines/areas/quality_safety/guide_on_pain/en/.
4. Agency for Healthcare Research and Quality (AHRQ). Pain Guidelines. www.guideline.gov/search/search.aspx?term=pain+guidelines.