Perhaps you should try some spelling variations:
"eastern european 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."
"eastern europe sources." » "fastern europe 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 ("eastern europe sources."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("eastern european sources.") OR ("east european sources."))) OR ("eastern europe sources.")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"eastern european sources.\") OR (\"east european sources.\"))) or (\"eastern europe sources.\"))".
• Removing quotes may allow a broader search: (((( eastern european sources. ) OR ( east european sources. ))) or ( eastern europe sources. )).
• Adding a wildcard symbol may retrieve word variants: (((("eastern european sources.") OR ("east european sources."))) or ("eastern europe sources."))*.