Perhaps you should try some spelling variations:
hieu luat » hieu qua
tinh dung » tin dung, tinh quang, tinh huong
tien soat » trien hoat, thien hoat, kiem soat
dung lan » dung luan, dung land, dung lam
van hieu » cao hieu
van tien » toan tien, van tuan
lan van » luan van, lang van, tan van

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( trinh dung lan van hieu luat ) or ( tinh dung (luan OR quan) van tien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh dung lan van hieu luat ) OR ( tinh dung (luan OR quan) van tien soat )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( trinh dung lan van hieu luat ) or ( tinh dung (luan OR quan) van tien soat ))".
• Adding a wildcard symbol may retrieve word variants: (( trinh dung lan van hieu luat ) or ( tinh dung (luan OR quan) van tien soat ))*.