Perhaps you should try some spelling variations:
phuong dan » phuong danh, phuong doan, huong dan
hieu lang » chieu sang, hieu quang, nhieu tang
canh manh » lanh manh, canh tranh, cach mang
doi hieu » doi chieu, doc hieu, doi hien
manh cua » doanh cua, ban cua
cua bang » chua bang, cua ban, cua dang
toan tap » toan ban

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

• If you are trying to use Boolean operators, they must be ALL CAPS: doi hieu lang - canh manh cua bang phuong dan ((toan tap) OR (van ban))~.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - canh manh cua bang phuong dan ((toan tap) or (van ban))*.