Perhaps you should try some spelling variations:
thieu quang » hieu quang, thien quan, trien quang
thieu sang » chieu sang, thieu khang, hieu lang
cong ngang » cong nhan, cong quang, cong lang
hanh hang » thanh hang, hang hang, hanh han
tong cong » trong cong, cong cong, dung cong
toan cao » toan ban
toan tap » toan ban
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 (thieu quang)) - hanh hang va tong cong ngang ((toan cao) or (toan tap))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sang) OR (thieu quang)) - hanh hang va tong cong ngang ((toan cao) OR (toan tap)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sang) OR (thieu quang)) - hanh hang va tong cong ngang ((toan cao) or (toan tap))".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sang) OR (thieu quang)) - hanh hang va tong cong ngang ((toan cao) or (toan tap))*.