Perhaps you should try some spelling variations:
have changed » has changed, a changed
changed sas » changed east, changed a, changed what
yuhan wang » yuan wang, yan wang, yuhuan huang
yuan kang » yuan wang, yuan chang, chan kang
can have » may have
sas cong » yan cong
cong van » congo can, duong van, cong sun

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: wang ((yuhan wang) or (yuan kang)) can have changed sas cong van ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: wang ((yuhan wang) OR (yuan kang)) can have changed sas cong van ;*.