Perhaps you should try some spelling variations:
"internationale conferentie opposition" » "international conference opposition" (Expand Search)
"international de opposition" » "international de l'opposition" (Expand Search), "international d'ete opposition" (Expand Search)
"internationale de opposition" » "internationale de l'opposition" (Expand Search), "internationale d'ete opposition" (Expand Search)

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("internationale des propositions") OR ((("international de opposition") OR ((((("internationale conferentie opposition") OR ("internationale de opposition"))) OR ("internationale politiek opposition"))))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"internationale des propositions\") OR (((\"international de opposition\") OR (((((\"internationale conferentie opposition\") OR (\"internationale de opposition\"))) OR (\"internationale politiek opposition\"))))))".
• Removing quotes may allow a broader search: (( internationale des propositions ) OR ((( international de opposition ) OR ((((( internationale conferentie opposition ) OR ( internationale de opposition ))) OR ( internationale politiek opposition )))))).
• Adding a wildcard symbol may retrieve word variants: (("internationale des propositions") OR ((("international de opposition") OR ((((("internationale conferentie opposition") OR ("internationale de opposition"))) OR ("internationale politiek opposition"))))))*.