Perhaps you should try some spelling variations:
dung phuong » dung thuong, dung chung, hoang phuong
theo hieu » theo chieu, theo tieu, thien hieu
hieu lang » chieu sang, hieu quang, nhieu tang
trang va » hang va
tran van » luan van
dan toan » van toan, dan than, manh toan
toan cao » toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: theo hieu lang - hanh ((trang va) OR (tran van)) ((bang phuong) or (dung phuong)) dan toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo hieu lang - hanh ((trang va) OR (tran van)) ((bang phuong) OR (dung phuong)) dan toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo hieu lang - hanh ((trang va) OR (tran van)) ((bang phuong) or (dung phuong)) dan toan cao".
• Adding a wildcard symbol may retrieve word variants: theo hieu lang - hanh ((trang va) OR (tran van)) ((bang phuong) or (dung phuong)) dan toan cao*.