Perhaps you should try some spelling variations:
patients risk » patient risk, patients links, patients si
risk wrong » risk among, risk along
wrong when » wrong keen, wrong what, wrong who
hua yang » hui yang, huang yang, hua jiang
hua cost » a cost, eu cost, run cost
da costa » _ costa, a cost
wan hua » wang hua, tan hua, wan musa

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: wan hua yang ((hua cost) OR (da costa)) patients risk wrong when ;~.
• Adding a wildcard symbol may retrieve word variants: wan hua yang ((hua cost) or (da costa)) patients risk wrong when ;*.