Perhaps you should try some spelling variations:
dung quang » dang quang, dung quan, luong quang
hieu soat » hieu suat, hieu luat, kiem soat
hieu hoat » hieu hoa, thien hoat, hieu luat
quang van » quang ban, quan van, quang uan
dien toan » dien thanh, dien thoai, dien hoa
luan han » luan hoan, luan phan, luan van
van dien » van tien, van hien, van kien

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 luan han ((hieu soat) or (hieu hoat)) ) or ( tin dung quang van dien toan ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh dung luan han ((hieu soat) OR (hieu hoat)) ) OR ( tin dung quang van dien toan )).
• Adding a wildcard symbol may retrieve word variants: (( trinh dung luan han ((hieu soat) or (hieu hoat)) ) or ( tin dung quang van dien toan ))*.