Citing sources according to APA guidelines

Retrieval dates not required for most online sources

Only include a retrieval date if an online source:

1. is designed to change over time, AND
2. is not archived (i.e., not stable).

This means that for changeable works that are archived (such as Cochrane reviews or articles on Wikipedia), you do not need to include a retrieval date in the reference. The archived versions are stable – they can be linked to using a permalink.

Which source types require a retrieval date?

Include a retrieval date for: 

• information on a website that updates frequently, such as statistics that are constantly refreshed;
• entries in online dictionaries;
• articles from the UpToDate database;
• maps generated with Google Maps;
• Twitter profiles and Facebook pages.

Format for retrieval dates in references

Use this format: