Perhaps you should try some spelling variations:
thanh day » thanh dat, thanh tay, thanh dam
va thanh » gia thanh, ban thanh, va tinh
te sach » toc sach
day cua » dai cua
cac dac » cac dan, cac dai, cac bac
sach ky » sac ky, sach y, sach ty
cac duc » cac du, cao duc, cac nuoc
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet

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: te sach ky ((mang may) OR (nang ma)) hoi. hieu va ((cac duc) OR (cac dac)) va thanh day cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((mang may) or (nang ma)) hoi. hieu va ((cac duc) OR (cac dac)) va thanh day cua tre~".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((mang may) or (nang ma)) hoi. hieu va ((cac duc) OR (cac dac)) va thanh day cua tre*.