Perhaps you should try some spelling variations:
hieu tieng » viet tieng, dien tieng, tiep tieng
hieu hien » bieu hien, dieu hien, chieu chien
tu sach » thu sach, su sach, te sach
cac dac » cac dan, cac dai, cac bac
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
cac tac » cac toc, cac bac, cac tai
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua
x hoi » xa hoi, o hoi, x ho

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. ((hieu tieng) or (hieu hien)) ((cac tac) or (cac dac)) va hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. ((hieu tieng) OR (hieu hien)) ((cac tac) OR (cac dac)) va hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((hieu tieng) or (hieu hien)) ((cac tac) or (cac dac)) va hanh di cua tre*.