1. UK Health Security Agent [Internet].London. Clinical audit: descriptive studies. [Cited Feb 2022]. Available from:https://www.gov.uk/guidance/clinical-audit-descriptive-studies
2. National Institute for Clinical Excellence (NICE) [Internet].Cornwall. Principles for best practice in clinical audit. [Cited Feb 2022]. Available from:https://www.nice.org.uk/media/default/About/what‐we‐do/Into‐practice/principles‐for‐best‐practice‐in‐clinical‐audit.pdf
3. Healthcare Quality Improvement Partnership [Internet].London. Best practice in clinical audit. [Cited Feb 2022]. Available from:https://www.rcr.ac.uk/sites/default/files/hqip_guide_for_best_practice_in_clinical_audit.pdf
4. Antenatal screening – the first and second trimester;Bonacquisto L;Australian Family Physician,2011