Perhaps you should try some spelling variations:
thieu khang » chieu khong, thieu quang
thanh trung » thanh tung
thieu sang » chieu sang, thieu quang, hieu lang
hang cong » dang cong, hang nong, bang cong
trung va » truong va, trang va, trung ha
cong dan » cong san, cong tan, huong dan
toan cao » toan ban
toan tap » toan ban
va hang » van hang, va nang, va lang

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thieu sang) or (thieu khang)) - thanh trung va hang cong dan ((toan cao) OR (toan tap))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sang) OR (thieu khang)) - thanh trung va hang cong dan ((toan cao) OR (toan tap)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sang) or (thieu khang)) - thanh trung va hang cong dan ((toan cao) OR (toan tap))".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sang) or (thieu khang)) - thanh trung va hang cong dan ((toan cao) OR (toan tap))*.