APA   Click to copy
Campbell, W. I., & Vowles, K. E. (2008). Practical methods for pain intensity measurements. Clinical Pain Management: Practice and Procedures, 12–27.

Chicago/Turabian   Click to copy
Campbell, William I, and Kevin E Vowles. “Practical Methods for Pain Intensity Measurements.” Clinical pain management: Practice and procedures (2008): 12–27.

MLA   Click to copy
Campbell, William I., and Kevin E. Vowles. “Practical Methods for Pain Intensity Measurements.” Clinical Pain Management: Practice and Procedures, Hodder Arnold New York, 2008, pp. 12–27.

@article{campbell2008a,
  title = {Practical methods for pain intensity measurements},
  year = {2008},
  journal = {Clinical pain management: Practice and procedures},
  pages = {12--27},
  publisher = {Hodder Arnold New York},
  author = {Campbell, William I and Vowles, Kevin E}
}