Perhaps you should try some spelling variations:
vanh dai » van dai, vanh tai, lanh dao
sach ky » sach y, sach ty, sach kem
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
sac ky » cac ky, sai ky
luc va » duc va, tuc va
loc va » hoc va
va cam » va cham, va cac, va cao
x hoi » xa hoi, o hoi, x ho

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang x hoi. hieu va cam ((luc va) OR (loc va)) vanh dai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sac ky)) nang x hoi. hieu va cam ((luc va) or (loc va)) vanh dai cua tre~".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sac ky)) nang x hoi. hieu va cam ((luc va) or (loc va)) vanh dai cua tre*.