Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
van hanh » van thanh, ban hanh, van anh
hanh de » hanh ve, hanh kem
hoc hoi » hoc khoi, hoc hoa, hoc noi
hieu ve » hieu va, hieu van
cac tuc » cac toc, cac tac, cac nuoc
cac tu » cac thu, cach tu, cac du
de cua » le cua, te cua, dieu cua
su sac » su sach, su cac, su xac
sac ky » cac ky, sai ky
ho hoi » hoa hoi, hoi hoi, co 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 sac ky nang ((ho hoi) or (hoc hoi)). hieu ve ((cac tuc) OR (cac tu)) van hanh de cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sac ky nang ((ho hoi) OR (hoc hoi)). hieu ve ((cac tuc) OR (cac tu)) van hanh de cua viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sac ky nang ((ho hoi) or (hoc hoi)). hieu ve ((cac tuc) OR (cac tu)) van hanh de cua viet*".