1. Measurement of pain;Huskisson;Lancet,1974
2. Pain intensity measurement in chronic low back pain;Strong;Clin J Pain,1991
3. Comparative responsiveness of verbal and numerical rating scales to measure pain intensity in patients with chronic pain;Chien;J Pain,2013
4. European palliative care research collaborative (EPCRC). Studies comparing numerical rating scales, verbal rating scales, and visual analogue scales for assessment of pain intensity in adults: a systematic literature review;Hjermstad;J Pain Symptom Manag,2011
5. The validity of pain intensity measures: what do the NRS, VAS, VRS, and FPS-R measure?;Thong;Scand J Pain,2018