Perhaps you should try some spelling variations:
dence network » dense network, defence network, dense networks
system report » system reform, system reforms, system recent
health dence » health device, health evidence, health science
health guide » health guido, earth guide, health grid

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