Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
chieu sach » chinh sach, chiet tach, chieu sang
manh tung » manh hung, thanh tung
tam dung » tam duong, tan dung, am dung
tac dung » sach dung, xay dung, tin dung
cong tap » cuong tap, cong tac, cong tan
tap doan » tap quan
doan cau » toan cau, doan dau, doan cap

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 quang) or (chieu sach)) - manh tung ((tam dung) OR (tac dung)) cong tap doan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu quang) OR (chieu sach)) - manh tung ((tam dung) OR (tac dung)) cong tap doan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu quang) or (chieu sach)) - manh tung ((tam dung) OR (tac dung)) cong tap doan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu quang) or (chieu sach)) - manh tung ((tam dung) OR (tac dung)) cong tap doan cau*.