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
tien soat » trien hoat, thien hoat, kiem soat
dung tan » dung toan, dung tai, dung san
van hieu » cao hieu
binh dan » minh danh, binh dinh, binh 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: (( tinh ((dung tan) or (duong tan)) van hieu soat ) or ( binh dan quang van tien 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 tien soat )).
• Adding a wildcard symbol may retrieve word variants: (( tinh ((dung tan) or (duong tan)) van hieu soat ) or ( binh dan quang van tien soat ))*.