Perhaps you should try some spelling variations:
dieu cua » dieu tra
su sach » vu sach
hieu ve » hieu va, hieu van
so sach » so sanh, bo sach, co sach
va dang » van dang, va nang, va lang
cao hoi » cau hoi, cao hoc, tao hoi
cac tuc » cac toc, cac tu, cac tac
tuc va » thuc va, truc va, tuc xa
ve cac » va cac, vien cac
co hoi » co hoc, co loi
v nang » va nang, vu nang, van nang
cua te » cua tu

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 sach) OR (so sach)) v nang ((cao hoi) OR (co hoi)). hieu ve cac tuc va dang dieu cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (so sach)) v nang ((cao hoi) or (co hoi)). hieu ve cac tuc va dang dieu cua te~".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (so sach)) v nang ((cao hoi) or (co hoi)). hieu ve cac tuc va dang dieu cua te*.