Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
cham duc » cham soc, pham duy, phan duc
sach ky » sac ky, sach y, sach ty
tai cua » thai cua, tai cuc, tri cua
tu sach » thu sach, su sach, te sach
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang ((x hoi) or (o hoi)). hieu van ((cham duc) or (pham duc)) van hanh tai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (o hoi)). hieu van ((cham duc) OR (pham duc)) van hanh tai cua viet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) or (o hoi)). hieu van ((cham duc) or (pham duc)) van hanh tai cua viet*.