Perhaps you should try some spelling variations:
hanh trinh » canh tranh, hanh chinh
chieu sang » chieu sach, chieu xanh, nhieu tang
hieu lang » hieu quang, nhieu tang, hieu van
trinh cua » tinh cua, trinh luat, trinh quan
cua dung » cua dang, cua dong, qua dung
cong dan » cong san, cong tan, cong dong
toan cao » toan ban, toan tap

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)) - hanh trinh cua dung ((cong dan) or (huong dan)) toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu lang) OR (chieu sang)) - hanh trinh cua dung ((cong dan) OR (huong dan)) toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu lang) OR (chieu sang)) - hanh trinh cua dung ((cong dan) or (huong dan)) toan cao".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu lang) OR (chieu sang)) - hanh trinh cua dung ((cong dan) or (huong dan)) toan cao*.