Perhaps you should try some spelling variations:
networks synthesis » nets synthesis
health assurance » health reassurance, health insurance, health assistance
networks systems » networks system, networked systems, network system
health evidence » health science

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: (( health evidence ((network synthesis) OR (network systems)) report ) OR ( health assurance ((networks synthesis) OR (networks systems)) report )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( health evidence ((network synthesis) or (network systems)) report ) or ( health assurance ((networks synthesis) OR (networks systems)) report ))".
• Adding a wildcard symbol may retrieve word variants: (( health evidence ((network synthesis) or (network systems)) report ) or ( health assurance ((networks synthesis) OR (networks systems)) report ))*.