Perhaps you should try some spelling variations:
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, hieu quang, nhieu tang
hoc hieu » hoc thieu, hoc hien, doc hieu
tuong va » truong va, thuong va, duong va
luong va » dung 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 - thanh ((tung va) OR (((tuong va) OR (luong va)))) thong cong ty dung lam~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu lang - thanh ((tung va) or (((tuong va) OR (luong va)))) thong cong ty dung lam~".
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - thanh ((tung va) or (((tuong va) OR (luong va)))) thong cong ty dung lam*.