Perhaps you should try some spelling variations:
canh trinh » canh tranh, hanh trinh, canh tinh
doc hieu » hoc thieu, hoc hien
trinh va » trinh van, trinh vat, trinh ve
cong tan » cong tac, cong thanh, cong ty
cong san » cong tac
toan cau » toan cao, toan ban, toan tap
va lang » va nang, hoa lang

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((doc hieu) or (toc thieu)) xanh - canh trinh va lang ((cong tan) OR (cong san)) toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc hieu) OR (toc thieu)) xanh - canh trinh va lang ((cong tan) OR (cong san)) toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc hieu) or (toc thieu)) xanh - canh trinh va lang ((cong tan) OR (cong san)) toan cau".
• Adding a wildcard symbol may retrieve word variants: ((doc hieu) or (toc thieu)) xanh - canh trinh va lang ((cong tan) OR (cong san)) toan cau*.