Perhaps you should try some spelling variations:
thieu sang » thieu khang, thieu quang, hieu lang
chieu sang » chieu sach, chieu xanh, hieu lang
cong thanh » dong thanh, cong trinh, cong tan
canh tinh » hanh tinh, manh tinh, canh tranh
tran tuan » tran xuan, tran thanh, tranh luan
he trong » he thong, he trung, le trong
tinh he » trinh he, hinh he, tinh ha
quang » quan

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 ((thieu sang) OR (chieu sang)) - canh tinh he trong cong thanh ((tran tuan) OR (tran quang))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sang) or (chieu sang)) - canh tinh he trong cong thanh ((tran tuan) OR (tran quang))~".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sang) or (chieu sang)) - canh tinh he trong cong thanh ((tran tuan) OR (tran quang))*.