Perhaps you should try some spelling variations:
thanh dan » thanh van, thanh dat, thanh dam
thu sach » tu sach, thuat sach, thuoc sach
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
dam tu » nam tu, cam tu, tam tu
xang x » nang x
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: thu sach ty xang x hoi. ((hieu ve) or (hieu va)) dam tu va ((thanh dan) OR (thanh san)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty xang x hoi. ((hieu ve) OR (hieu va)) dam tu va ((thanh dan) OR (thanh san)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty xang x hoi. ((hieu ve) or (hieu va)) dam tu va ((thanh dan) OR (thanh san)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ty xang x hoi. ((hieu ve) or (hieu va)) dam tu va ((thanh dan) OR (thanh san)) cua tre*.