Perhaps you should try some spelling variations:
thieu sang » thieu khang, thieu quang, hieu lang
chieu sang » chieu sach, chieu xanh, hieu lang
hanh sinh » hanh tinh, hanh dinh, hinh sinh
vat nhung » va nhung, vap nhung, vai nhung
cong tan » cong tac, cong thanh, cong ty
cong san » cong tac
toan tap » toan ban

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 (chieu sang)) - hanh sinh vat nhung ((cong tan) OR (cong san)) toan tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sang) OR (chieu sang)) - hanh sinh vat nhung ((cong tan) OR (cong san)) toan tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sang) or (chieu sang)) - hanh sinh vat nhung ((cong tan) OR (cong san)) toan tap".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sang) or (chieu sang)) - hanh sinh vat nhung ((cong tan) OR (cong san)) toan tap*.