Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh quang
hieu soat » hieu suat, hieu hoat, hieu luat
tinh quan » tinh quang, trinh quan, tin quan
quan quan » quan quang, qua quan, quan luan
quan dang » quang dang, quan lang, quan dong
dieu hat » dieu hanh, dieu khac, dieu can
lan van » lang van, tan van, san van

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

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