Perhaps you should try some spelling variations:
khien bang » phien ban, khien dong
hien sang » hien trang, chieu sang, thien bang
thong cua » thong quan, thong tu, huong cua
dung cong » dung trong
cong san » cong tac
san toan » van toan, dan toan, manh toan
toan cao » toan ban, toan tap
hang ca » hang va, nang cao, hang tai

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((hien sang) OR (khien bang)) - hanh ((thong cua) or (hang ca)) dung cong san toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hien sang) OR (khien bang)) - hanh ((thong cua) OR (hang ca)) dung cong san toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hien sang) OR (khien bang)) - hanh ((thong cua) or (hang ca)) dung cong san toan cao".
• Adding a wildcard symbol may retrieve word variants: hoc ((hien sang) OR (khien bang)) - hanh ((thong cua) or (hang ca)) dung cong san toan cao*.