Perhaps you should try some spelling variations:
international congress » international conference
international centre » international theatre, international context, international case
mechanical science » mechanism science, clinical science, mechanical efficiency
mechanical stretch » mechanical strength, mechanical stress, mechanical stresses
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 science) OR (mechanical stretch))s) OR (((mechanical science) OR (mechanical stretch)))), courses AND lectures.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((international centre) or (international congress)) for ((((mechanical science) OR (mechanical stretch))s) or (((mechanical science) OR (mechanical stretch)))), courses and lectures".
• Adding a wildcard symbol may retrieve word variants: ((international centre) or (international congress)) for ((((mechanical science) OR (mechanical stretch))s) or (((mechanical science) OR (mechanical stretch)))), courses and lectures*.