Perhaps you should try some spelling variations:
trinh quan » tinh quang, trinh luat, trinh han
hanh trinh » canh tranh, hanh chinh
nhung cong » dung cong, hang cong, nhung don
thong cong » trong cong, tong cong, thong thong
chieu qua » khien qua, hieu cua, hieu quan
tan phan » toan phan, than phan, van phan
phan dau » phan tu, hang dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho ((chieu qua) or (hieu qua)) - hanh trinh quan ((nhung cong) OR (thong cong)) tan phan dau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho ((chieu qua) OR (hieu qua)) - hanh trinh quan ((nhung cong) OR (thong cong)) tan phan dau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((chieu qua) or (hieu qua)) - hanh trinh quan ((nhung cong) OR (thong cong)) tan phan dau".
• Adding a wildcard symbol may retrieve word variants: ho ((chieu qua) or (hieu qua)) - hanh trinh quan ((nhung cong) OR (thong cong)) tan phan dau*.