Perhaps you should try some spelling variations:
kho tang » cao tang
hieu van » hieu va, thien van, lieu va
sach kho » bach khoa, sach dao, sach nha
trinh vi » trinh va, trinh ve, trinh viet
su sach » so sach, vu sach
tang xa » trang xa, tang ma, lang xa
van bac » van ban, van bao, van hac
cua tre » cuu tre, cua triet, dua tren
cua te » cua tu
luc va » duc va, tuc va
loc va » hoc va

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: su sach kho tang xa hoi. hieu van bac ((loc va) OR (luc va)) trinh vi ((cua tre) OR (cua te))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach kho tang xa hoi. hieu van bac ((loc va) or (luc va)) trinh vi ((cua tre) OR (cua te))~".
• Adding a wildcard symbol may retrieve word variants: su sach kho tang xa hoi. hieu van bac ((loc va) or (luc va)) trinh vi ((cua tre) OR (cua te))*.