Perhaps you should try some spelling variations:
thieu khang » chieu khong, thieu quang
thieu sang » chieu sang, thieu quang, hieu lang
tuong cong » truong cong, trong cong, tong cong
truong va » truong dai, truong cao, truong dao
trung va » trang va, trung ha, trung tam
cong dan » cong san, cong tan, huong dan
dan toan » van toan, dan than, manh toan
toan cau » toan cao, toan ban, toan tap

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)) - hanh ((trung va) or (truong va)) tuong cong dan toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sang) OR (thieu khang)) - hanh ((trung va) OR (truong va)) tuong cong dan toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sang) OR (thieu khang)) - hanh ((trung va) or (truong va)) tuong cong dan toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sang) OR (thieu khang)) - hanh ((trung va) or (truong va)) tuong cong dan toan cau*.