Perhaps you should try some spelling variations:
thanh khong » thanh hong, thinh khong, thanh chuong
nganh nong » nganh cong
can thanh » ban thanh, van thanh, cac thanh
khong khi » khong he
nganh yng » nganh cong, nganh y
su sach » so sach, vu sach
su can » su van, su cao, tu can

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: (( su can thanh khong khi đong luc ) OR ( su sach ((nganh yng) OR (nganh nong)) khi đong luc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su can thanh khong khi đong luc ) or ( su sach ((nganh yng) OR (nganh nong)) khi đong luc ))~".
• Adding a wildcard symbol may retrieve word variants: (( su can thanh khong khi đong luc ) or ( su sach ((nganh yng) OR (nganh nong)) khi đong luc ))*.