Perhaps you should try some spelling variations:
international congress » international conference
international centre » international theatre, international context, international case
mechanical sciences » mechanical science, chemical sciences, mechanical stresses
technical sciences » medical sciences, chemical sciences, technical advances
lectures » lecture

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 centre) OR (international congress)) for ((mechanical sciences) OR (technical sciences)), courses AND lectures.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((international centre) or (international congress)) for ((mechanical sciences) OR (technical sciences)), courses and lectures".
• Adding a wildcard symbol may retrieve word variants: ((international centre) or (international congress)) for ((mechanical sciences) OR (technical sciences)), courses and lectures*.