Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
van hanh » van thanh, ban hanh, van anh
cac duc » cao duc, cac dac, cac nuoc
hanh di » hanh vi, hanh de, hang di
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
di cua » dai cua, doi cua, de cua
su sai » su tai, su hai, su dai
sai ky » sac ky
ma hoi » xa hoi, ma hoa, me hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sai ky nang ((ma hoi) or (mai hoi)). hieu ve ((cac duc) OR (cac du)) van hanh di cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sai ky nang ((ma hoi) OR (mai hoi)). hieu ve ((cac duc) OR (cac du)) van hanh di cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sai ky nang ((ma hoi) or (mai hoi)). hieu ve ((cac duc) OR (cac du)) van hanh di cua triet".
• Adding a wildcard symbol may retrieve word variants: su sai ky nang ((ma hoi) or (mai hoi)). hieu ve ((cac duc) OR (cac du)) van hanh di cua triet*.