GRANT, A., DEAN, S., HAY-SMITH, J., HAGEN, S., MCCLURG, D., TAYLOR, A., KOVANDZIC, M. and BUGGE, C. 2019. Effectiveness and cost-effectiveness randomised controlled trial of basic versus biofeedback-mediated intensive pelvic floor muscle training for female stress or mixed urinary incontinence: protocol for the OPAL (optimising pelvic floor exercises to achieve long-term benefits) trial mixed methods longitudinal qualitative case study and process evaluation. BMJ open [online], 9(2), article ID e024152. Available from: https://doi.org/10.1136/bmjopen-2018-024152