Perhaps you should try some spelling variations:
duong tan » duong tuan, duong van, duong tai
hieu soat » hieu suat, hieu hoat, hieu luat
dan quang » dang quang, doan quang, van quang
quang van » quang ban, quan van, quang uan
kien soat » kiem soat, bien soan, kien hoa
dung tan » dung toan, dung tai, dung san
van hieu » cao hieu
binh dan » minh danh, binh dinh, binh luan
van kien » van tien, van hien, van chien

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 tan) OR (duong tan)) van hieu soat ) or ( binh dan quang van kien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh ((dung tan) OR (duong tan)) van hieu soat ) OR ( binh dan quang van kien soat )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh ((dung tan) OR (duong tan)) van hieu soat ) or ( binh dan quang van kien soat ))".
• Adding a wildcard symbol may retrieve word variants: (( tinh ((dung tan) OR (duong tan)) van hieu soat ) or ( binh dan quang van kien soat ))*.