Perhaps you should try some spelling variations:
thieu sang » chieu sang, thieu khang, thieu quang
hieu quang » thieu quang, hieu quan, hieu qua
hang hang » nang hang, cang thang, hung thang
tong cong » trong cong, cong cong, dung cong
cong luan » tong luan, cong tuan, dong luan
va tong » va thong, va tuong, va trong

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thieu sang) or (hieu quang)) - hang hang va tong cong luan van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sang) OR (hieu quang)) - hang hang va tong cong luan van ban.
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sang) or (hieu quang)) - hang hang va tong cong luan van ban*.