Perhaps you should try some spelling variations:
truong cong » trong cong, truong dong, truong long
thanh tran » thanh trang, thanh toan, thanh tra
thuong con » thuong dong, thong cong, thuong chi
sach tranh » canh tranh
hieu sang » chieu sang, hieu quang, nhieu tang
hieu lang » chieu sang, hieu quang, nhieu tang
tranh ban » trinh ban, tranh hang, tranh luan
tran van » luan van

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu sang) or (hieu lang)) - thanh tran van ((thuong con) OR (truong cong)) sach tranh ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu lang)) - thanh tran van ((thuong con) OR (truong cong)) sach tranh ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) or (hieu lang)) - thanh tran van ((thuong con) OR (truong cong)) sach tranh ban".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) or (hieu lang)) - thanh tran van ((thuong con) OR (truong cong)) sach tranh ban*.