1. Studies Comparing Numerical Rating Scales, Verbal Rating Scales, and Visual Analogue Scales for Assessment of Pain Intensity in Adults: A Systematic Literature Review 
Marianne Jensen Hjermstad, PhD, Peter M. Fayers, PhD, Dagny F. Haugen, MD, PhD, Augusto Caraceni, MD, Geoffrey W. Hanks, DSc (Med), MB, Jon H. Loge, MD, PhD, Robin Fainsinger, MD, Nina Aass, MD, Stein Kaasa, MD, PhD 
Journal of Pain and Symptom Management 
Volume 41, Issue 6, Pages (June 2011)
DOI: /j.jpainsymman
Copyright © 2011 U.S. Cancer Pain Relief Committee Terms and Conditions

2. Fig. 1 Flowchart of the literature review and selection of papers.
Journal of Pain and Symptom Management  , DOI: ( /j.jpainsymman )
Copyright © 2011 U.S. Cancer Pain Relief Committee Terms and Conditions