Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
canh trinh » canh tranh, hanh trinh, canh tinh
hoc hieu » hoc thieu, hoc hien, hoc dieu
doc hieu » toc thieu, hoc thieu, hoc hien
trinh va » trinh van, trinh vat, trinh ve
cong san » cong tac
phan dau » phan tu, hang dau
phan cac » nhan cach, phan lap, phan van

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) OR (doc hieu)) manh - canh trinh va nhung cong san ((phan dau) or (phan cac))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc hieu) OR (doc hieu)) manh - canh trinh va nhung cong san ((phan dau) OR (phan cac)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc hieu) OR (doc hieu)) manh - canh trinh va nhung cong san ((phan dau) or (phan cac))".
• Adding a wildcard symbol may retrieve word variants: ((hoc hieu) OR (doc hieu)) manh - canh trinh va nhung cong san ((phan dau) or (phan cac))*.