Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Atrial septal defect:

This text has been unreferenced on Wikipedia for a very long time. If you can't find a source, be bold and remove it!

"

Once someone is found to have an atrial septal defect, a determination of whether it should be corrected is typically made. If the atrial septal defect is causing the right ventricle to enlarge a secundum atrial septal defect should generally be closed.[1] If the ASD is not causing problems the defect may simply be checked every two or three years.[1] Methods of closure of an ASD include surgical closure and percutaneous closure.[citation needed]