Perhaps you should try some spelling variations:
dung phuong » dung thuong, bang phuong, dung chung
chieu sang » chieu sach, chieu xanh, nhieu tang
thanh tung » thanh cong
hieu lang » hieu quang, nhieu tang, hieu van
doan toan » dan toan, doanh hoan, doan trang
doan tuan » doan quan, doanh luan, doan quang
tung va » trung va, tuong va, dung va
va dung » van dung, va duong, vat dung

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

• Performing a fuzzy search may retrieve terms with similar spellings: thien ((hieu lang) OR (chieu sang)) - thanh tung va dung phuong ((doan toan) or (doan tuan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thien ((hieu lang) OR (chieu sang)) - thanh tung va dung phuong ((doan toan) OR (doan tuan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thien ((hieu lang) OR (chieu sang)) - thanh tung va dung phuong ((doan toan) or (doan tuan)) cau".
• Adding a wildcard symbol may retrieve word variants: thien ((hieu lang) OR (chieu sang)) - thanh tung va dung phuong ((doan toan) or (doan tuan)) cau*.