Nomikos, Polykarpos Angelos, Hall, Michelle, Fuller, Amy, Millar, Bonnie, Ogollah, Reuben, Valdes, Ana, Doherty, Michael, Walsh, David A., Das Nair, Roshan, Abhishek, A., "Fidelity assessment of nurse-led non-pharmacological package of care for knee pain in the package development phase of a feasibility randomised controlled trial based in secondary care: A mixed methods study", BMJ Open, 2021