Perhaps you should try some spelling variations:
thanh vi » thanh va, thanh ve, nhanh vi
te sach » toc sach
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
bac so » bac son, bac si, bac bo
so van » su van, vo van
ve bac » ve bao, ve cac, ve ban
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty xang ((x hoi) OR (o hoi)). hieu ve bac so van ((thanh vi) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty xang ((x hoi) OR (o hoi)). hieu ve bac so van ((thanh vi) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty xang ((x hoi) OR (o hoi)). hieu ve bac so van ((thanh vi) or (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ty xang ((x hoi) OR (o hoi)). hieu ve bac so van ((thanh vi) or (hanh vi)) cua tre*.