@inbook{1164449874, author={John Murtagh and Clare Murtagh}, title={O}, booktitle={Murtagh’s General Practice Companion Handbook, 7e}, publisher={McGraw-Hill Education (Australia) Pty Ltd}, address={Sydney, Australia}, year={2019}, url={murtagh.mhmedical.com/content.aspx?aid=1164449874} }