Perhaps you should try some spelling variations:
"eastern european sources." » "eastern europe sources.", "western europe sources.", "eastern european studies.", "eastern european series.", "eastern european southern.", "fastern european sources."
"east european sources." » "east european studies.", "east european series.", "east european southern.", "fast european sources."
"fastern europe sources." » "eastern europe sources.", "western europe sources.", "eastern europe's sources."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (((("eastern european sources.") or ("east european sources."))) or ("fastern europe sources."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("eastern european sources.") OR ("east european sources."))) OR ("fastern europe sources.")).
• Removing quotes may allow a broader search: (((( eastern european sources. ) or ( east european sources. ))) or ( fastern europe sources. )).
• Adding a wildcard symbol may retrieve word variants: (((("eastern european sources.") or ("east european sources."))) or ("fastern europe sources."))*.