Perhaps you should try some spelling variations:
nang than » nang thanh, sang than, nang phan
hieu van » hieu va, thien van, lieu va
than cua » nhan cua, thai cua, ban cua
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, cao hoc, tao hoi
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
va nang » van nang, da nang, cam nang
cua tre » cua te, cuu tre, cua triet
co hoi » co hoc, co loi

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 ((cao hoi) or (co hoi)). hieu van cau duc va nang than cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((cao hoi) OR (co hoi)). hieu van cau duc va nang than cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((cao hoi) or (co hoi)). hieu van cau duc va nang than cua tre*.