* "The Andy Griffith Show" aired from 1960 to 1968, so there's no single release date for the entire series.
* "Barney Hosts a Summit Meeting" is not a recognized episode title. You might have the title slightly off.
* The episode number "8-21" is not a standard way of referencing episodes. It's possible this is a custom numbering system, but it's not widely recognized.
To find the release date of the episode you're looking for, you need to provide more information:
* The correct episode title: Check online resources like IMDb or The Andy Griffith Show Wiki to confirm the correct episode name.
* The season and episode number: This will help you narrow down the search.
* The original air date: If you know the original air date, you can use that to identify the episode.
Once you have this information, you can easily find the release date of the episode you're looking for.