Perhaps you should try some spelling variations:
dung thai » duong thai, dung hai, dung thi
hieu soat » hieu suat, hieu hoat, hieu luat
dung quan » dung quang, dung luan, luong quan
tien soat » trien hoat, thien hoat, kiem soat
van hieu » cao hieu
quan van » luan van, quan va, quan luan
van tien » toan tien, van tuan

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

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