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
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
nam hoc » nam moc, nam hoi, am hoc
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo

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