Perhaps you should try some spelling variations:
doanh quang » doan quang, doanh quan, doanh luan
chieu sang » chieu sach, chieu xanh, nhieu tang
quang hang » quang hoang, quang khang, quang thang
hieu lang » hieu quang, nhieu tang, hieu van
hang cong » dang cong, hang nong, bang cong
cong tan » cong tac, cong san, cong thanh
tan nhan » tran nhan, tao nhan, van nhan
nhan cay » nhanh cay, nham cay, nhan cach

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((hieu lang) or (chieu sang)) - toan doanh quang hang cong tan nhan cay~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu lang) OR (chieu sang)) - toan doanh quang hang cong tan nhan cay.
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu lang) or (chieu sang)) - toan doanh quang hang cong tan nhan cay*.