Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hanh tai » thanh tai, hang tai, han tai
hoc sach » hoc sinh, hoc cac, hoc anh
van hanh » van thanh, ban hanh, van anh
hieu ve » hieu va, hieu van
tai cua » thai cua, tai cuc, tri cua
luc van » luoc van, luu van, duc van
cac luc » cau luc, coc luc, cac nuoc
tu sach » thu sach, su sach, te sach
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((((tu sach) or (toc sach))) or (hoc sach)) ky lang xa hoi. hieu ve cac luc van hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((tu sach) OR (toc sach))) OR (hoc sach)) ky lang xa hoi. hieu ve cac luc van hanh tai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((((tu sach) or (toc sach))) or (hoc sach)) ky lang xa hoi. hieu ve cac luc van hanh tai cua tre*.