You can use Linked Table Manager to help.
Go to Tools>Database Utilities>Linked Table Manager
Now you can check for each linked tables for its source container.
If the Linked Table Manger is not installed, you can type the line below in Immediate Window and find it out. Press Ctrl + G to open the Immediate window and replace ALinkedTableNameHere with a linked table name you want to find its source.
? Mid(CurrentDb.TableDefs("ALinkedTableNameHere").Connect, 11)