Perhaps you should try some spelling variations:
chieu sang » chieu sach, chieu xanh, nhieu tang
thong cong » trong cong, tong cong, thong thong
hieu lang » hieu quang, nhieu tang, hieu van
tuong va » truong va, thuong va, luong va
dung lam » dung luan, dung tai, dung dat
tung va » trung va, dung va, vung va
ty dung » tay dung, ly dung, te dung

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

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu lang) OR (chieu sang)) - thanh ((tung va) OR (tuong va)) thong cong ty dung lam~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu lang) OR (chieu sang)) - thanh ((tung va) or (tuong va)) thong cong ty dung lam~".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu lang) OR (chieu sang)) - thanh ((tung va) or (tuong va)) thong cong ty dung lam*.