Perhaps you should try some spelling variations:
nang doc » nang luc
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
nang du » nang tu, nang luc
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
cao va » cao van, tao va, co va

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 ky lang xa hoi. hieu ve cac ((cao va) or (ban va)) ((nang du) or (nang doc)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang xa hoi. hieu ve cac ((cao va) OR (ban va)) ((nang du) OR (nang doc)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang xa hoi. hieu ve cac ((cao va) or (ban va)) ((nang du) or (nang doc)) cua tre*.