Perhaps you should try some spelling variations:
trien hoat » tien hoa
van trien » van tien, va trien, van tren
tinh quan » tinh quang, trinh quan, tin quan
quan tran » quang tran, quan tren, xuan tran
hieu soat » hieu suat, hieu hoat, hieu luat
van hieu » cao hieu
luan » lan

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 van trien hoat ) or ( tinh quan tran van hieu soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh dung luan van trien hoat ) OR ( tinh quan tran van hieu soat ))*.