Perhaps you should try some spelling variations:
nhung phuong » dung phuong, nhu phuong, truong phuong
phuong dan » phuong danh, phuong doan, huong dan
hieu sang » chieu sang, hieu quang, nhieu tang
hieu lang » chieu sang, hieu quang, nhieu tang
trinh cua » tinh cua, trinh quan, trinh luan
dan toan » van toan, dan than, manh toan
toan ban » van ban

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)) - hanh ((trinh cua) or (trinh luat)) nhung phuong dan toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu lang)) - hanh ((trinh cua) OR (trinh luat)) nhung phuong dan toan ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) OR (hieu lang)) - hanh ((trinh cua) or (trinh luat)) nhung phuong dan toan ban".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) OR (hieu lang)) - hanh ((trinh cua) or (trinh luat)) nhung phuong dan toan ban*.