Cunningham-Burley, R., Roche, J., Fairhurst, C., Cockayne, S., Hewitt, C., Iles-Smith, H., & Torgerson, D. (2020). Enclosing a pen to improve response rate to postal questionnaire: an embedded randomised controlled trial. F1000Research, 9, 577. https://doi.org/10.12688/f1000research.23651.1