Perhaps you should try some spelling variations:
duong tan » duong tuan, duong van, duong tai
quang uan » quang tuan, quang ban, quang tran
kiem toan » ke toan, kiem tra
dung tan » dung toan, dung tai, dung san
van hieu » cao hieu
van kiem » va kiem, van kien, van hien
uan van » luan van, quan van, tan van

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

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