Perhaps you should try some spelling variations:
"conferencia internacional." » "convencion internacional.", "comercial internacional.", "experiencia internacional."
"conferencia ministerio." » "conferencia ministerial.", "conferencia magistral.", "conferencia monetaria."
"conferencia nacional." » "conciencia nacional.", "confederacion nacional.", "conferencia magistral."

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("conferencia nacional.") OR ("conferencia internacional."))) OR ("conferencia ministerio."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"conferencia nacional.\") OR (\"conferencia internacional.\"))) or (\"conferencia ministerio.\"))~".
• Removing quotes may allow a broader search: (((( conferencia nacional. ) OR ( conferencia internacional. ))) or ( conferencia ministerio. ))~.
• Adding a wildcard symbol may retrieve word variants: (((("conferencia nacional.") OR ("conferencia internacional."))) or ("conferencia ministerio."))*.