Perhaps you should try some spelling variations:
international astronomical » international economics, international economic
astronomical observations » astrological observations, astronomy observations, meteorological observations
economique internationale » economics international, economy international
politique internationale » policy international

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: ((international astronomical) OR (observations astronomical)) union/union ((astronomical observations) OR (((economique internationale) OR (politique internationale)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((international astronomical) or (observations astronomical)) union/union ((astronomical observations) or (((economique internationale) OR (politique internationale))))".
• Adding a wildcard symbol may retrieve word variants: ((international astronomical) or (observations astronomical)) union/union ((astronomical observations) or (((economique internationale) OR (politique internationale))))*.