Technically speaking all you really need to store is the Refresh Token and some kind of flag type identifier that tells you if its a Facebook or Google Refresh Token.   Then you can query the API for what ever information you need. Storing the User Id would be a good idea becouse if they logout then reauth you will still know who it is even though the refresh token has changed.    anything else is kind of over kill really as you will be getting that information back from the API anyway when you make your calls.    

You could if you want store there Name and most recent picture that might be nice to display before you have fetched there information. Then update any changes to your data after you access the API for the first time.  But its basically up to you how you want to design things, and what kind of application we are talking about here.

Database table structure for storing SSO information for FB or Google+
I'm looking for a book with the description of basic types of graphs, terminology used in this field of Mathematics and main theorems. All in all, a good book to start with to be able to understand other more complicated works.
