Perhaps you should try some spelling variations:
cong ngang » cong nhan, cong quang, cong lang
hieu lang » chieu sang, hieu quang, nhieu tang
trinh cua » trinh luat, trinh quan, trinh luan
cong vang » cong lang, cong quang, cong san
hoi hieu » hoi phieu, hoi tieu, moi hieu
tinh cua » sinh cua, tinh chat, tranh cua
toan tap » toan ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoi hieu lang - hanh ((trinh cua) or (tinh cua)) dung ((cong vang) OR (cong ngang)) toan tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoi hieu lang - hanh ((trinh cua) OR (tinh cua)) dung ((cong vang) OR (cong ngang)) toan tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoi hieu lang - hanh ((trinh cua) or (tinh cua)) dung ((cong vang) OR (cong ngang)) toan tap".
• Adding a wildcard symbol may retrieve word variants: hoi hieu lang - hanh ((trinh cua) or (tinh cua)) dung ((cong vang) OR (cong ngang)) toan tap*.