Perhaps you should try some spelling variations:
thanh trung » thanh tung
thong cong » trong cong, tong cong, thong thong
hieu tach » hieu cach, chiet tach, chieu sach
doc hieu » toc thieu, hoc thieu, hoc hien
va thong » va thuong, va phuong, he thong
cong dan » cong san, cong tan, huong dan
than tap » han tap, phan tap, than cap
toan tap » toan ban

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: doc hieu tach - ((canh tranh) OR (thanh trung)) va thong cong dan ((than tap) OR (toan tap))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu tach - ((canh tranh) or (thanh trung)) va thong cong dan ((than tap) OR (toan tap))~".
• Adding a wildcard symbol may retrieve word variants: doc hieu tach - ((canh tranh) or (thanh trung)) va thong cong dan ((than tap) OR (toan tap))*.