Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
thu sach » tu sach, thuat sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
cua viet » ca viet, hoa viet, cua vat
lai hoi » dai hoi, lai hoa, lai roi
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, mai doi
hanh di » hanh vi, hanh de, hang di
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang ((mai hoi) or (lai hoi)). hieu hien ((cac nuoc) or (cam xuc)) van hanh di cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((mai hoi) OR (lai hoi)). hieu hien ((cac nuoc) OR (cam xuc)) van hanh di cua viet.
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((mai hoi) or (lai hoi)). hieu hien ((cac nuoc) or (cam xuc)) van hanh di cua viet*.