Perhaps you should try some spelling variations:
thieu khang » chieu khong, thieu quang
thanh trung » thanh tung
nhung duong » nhung dung, nhung huong, nhung tuong
thieu sang » chieu sang, thieu quang, hieu lang
duong manh » duong van
manh toan » thanh toan, anh tuan, tinh toan
trung va » truong va, trang va, trung ha
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)) - thanh trung va nhung duong manh toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sang) OR (thieu khang)) - thanh trung va nhung duong manh toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sang) OR (thieu khang)) - thanh trung va nhung duong manh toan cau*.