Perhaps you should try some spelling variations:
hieu soat » hieu hoat, hieu luat, kiem soat
hieu suat » hieu luat, hieu qua
dung dat » dung va, dung tai
van kien » van tien, van hien, van chien
kien hoa » dien hoa, tien hoa, kien ha
dat van » dao van, dat va, dam van
tin » tinh
luan » quan, lan

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tin dung luan van ((hieu soat) OR (hieu suat)) ) or ( trinh dung dat van kien hoa ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tin dung luan van ((hieu soat) OR (hieu suat)) ) OR ( trinh dung dat van kien hoa ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tin dung luan van ((hieu soat) OR (hieu suat)) ) or ( trinh dung dat van kien hoa ))*".