Perhaps you should try some spelling variations:
german health » human health, urban health
guan health » human health, afghan health, urban health
iran health » urban health, migrant health, human health
tang min » chang min, sang minh, yang mind
min hong » amin hong, tin hong, min hyoung
wang » wing, wan, lang
tang » thang
tan » than

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: wang yan ((guan health) OR (((iran health) OR (german health)))) gain tang min hong tan ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "wang yan ((guan health) or (((iran health) OR (german health)))) gain tang min hong tan ;~".
• Adding a wildcard symbol may retrieve word variants: wang yan ((guan health) or (((iran health) OR (german health)))) gain tang min hong tan ;*.