Perhaps you should try some spelling variations:
phuong dan » phuong danh, phuong doan, huong dan
theo hieu » theo chieu, theo tieu, thien hieu
hieu lang » chieu sang, hieu quang, nhieu tang
tang tuan » trang tuan, tang quan, tang tan
tang luan » dung luan
toan cau » toan ban, toan tap, toan tai
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 ((tang tuan) or (tang luan)) doan phuong dan ((toan cau) OR (toan cao))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo hieu lang - hanh ((tang tuan) OR (tang luan)) doan phuong dan ((toan cau) OR (toan cao)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo hieu lang - hanh ((tang tuan) or (tang luan)) doan phuong dan ((toan cau) OR (toan cao))".
• Adding a wildcard symbol may retrieve word variants: theo hieu lang - hanh ((tang tuan) or (tang luan)) doan phuong dan ((toan cau) OR (toan cao))*.