Perhaps you should try some spelling variations:
international convention » national convention, international conference
international theatre » international treaties, international trade, international test
international context » international congress, international conference
technical sciences » medical sciences, chemical sciences, technical advances

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 convention) OR (international cooperation))) OR (international theatre))) OR (international context)) for technical sciences, courses AND lecture.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((international convention) OR (international cooperation))) or (international theatre))) or (international context)) for technical sciences, courses and lecture".
• Adding a wildcard symbol may retrieve word variants: ((((((international convention) OR (international cooperation))) or (international theatre))) or (international context)) for technical sciences, courses and lecture*.