Perhaps you should try some spelling variations:
thanh trung » thanh tung
chieu sang » chieu sach, chieu xanh, hieu lang
ho chieu » theo chieu, hoc thieu, doi chieu
cong tac » cong ty
tac toan » tap toan, tam toan, hach toan
toan cau » toan cao, toan ban, toan tap
cua van » cua ban, cua dan, cua can

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: ho chieu sang - thanh trung ((cua van) OR (cua vat)) cong tac toan cau~.
• Adding a wildcard symbol may retrieve word variants: ho chieu sang - thanh trung ((cua van) or (cua vat)) cong tac toan cau*.