Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van tuan » van quan, anh tuan
su sach » so sach, vu sach
va nang » van nang, da nang, cam nang
van cac » van hac, van cau, van bac
cac cac » cac cach, ca cac, cac bac
cua tre » cua te, cuu tre, cua triet
v nang » vu nang, van nang, voi nang
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: su sach ((v nang) or (va nang)) x hoi. hieu van cac cac ((van tuan) OR (van ban)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((v nang) OR (va nang)) x hoi. hieu van cac cac ((van tuan) OR (van ban)) dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((v nang) or (va nang)) x hoi. hieu van cac cac ((van tuan) OR (van ban)) dai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((v nang) or (va nang)) x hoi. hieu van cac cac ((van tuan) OR (van ban)) dai cua tre*.