O'Flynn Norma, Vaughan Mark, Kelley Kate
National Clinical Guideline Centre Acute and Chronic Conditions, Royal College of Physicians, London.;
Meddygfa Avenue Villa Surgery Heol Brynmor, Llanelli, Wales.
Br J Gen Pract. 2014 Jun;64(623):314-5. doi: 10.3399/bjgp14X680329.