Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
doc sach » hoc sach, toc sach, nuoc sach
hieu van » hieu va, thien van, lieu va
dan hanh » dang hanh, dan khanh, dan thanh
hanh dai » hanh tai, hanh dao, vanh dai
su sach » so sach, vu sach
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
nam hoc » nam moc, nam hoi, am hoc
cua tre » cua te, cuu tre, cua triet

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) or (thu sach))) or (doc sach)) ky tang xa hoi. hieu van nam hoc dan hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((su sach) OR (thu sach))) OR (doc sach)) ky tang xa hoi. hieu van nam hoc dan hanh dai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((((su sach) or (thu sach))) or (doc sach)) ky tang xa hoi. hieu van nam hoc dan hanh dai cua tre*.