Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
hieu va » lieu va
cac toc » cac toi, cac nuoc, cac thoi
dan dai » dat dai, can dai, dan dat
cua tre » cua te, cuu tre, cua triet
toc xa » tuc xa, toc ta, hoc xa
xa dan » ca dan, xa dai, va dan

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 tang xa hoi. ((hieu va) OR (hieu qua)) cac toc xa dan dai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky tang xa hoi. ((hieu va) OR (hieu qua)) cac toc xa dan dai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky tang xa hoi. ((hieu va) OR (hieu qua)) cac toc xa dan dai cua tre*.