Perhaps you should try some spelling variations:
vien nganh » vien thanh
hanh trang » thanh trung, canh tranh, hanh trinh
hiem ngan » kim ngan, viem gan
trang va » tran van, hang va
cong dan » cong tan, huong dan, cong dong
cong san » cong tac
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 ((hiem ngan) or (vien nganh)) - hanh trang va nhung ((cong dan) OR (cong san)) toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hiem ngan) OR (vien nganh)) - hanh trang va nhung ((cong dan) OR (cong san)) toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hiem ngan) or (vien nganh)) - hanh trang va nhung ((cong dan) OR (cong san)) toan cao".
• Adding a wildcard symbol may retrieve word variants: hoc ((hiem ngan) or (vien nganh)) - hanh trang va nhung ((cong dan) OR (cong san)) toan cao*.