Perhaps you should try some spelling variations:
sach ky » sac ky, sach ty, sach kem
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) OR (sach y)) tang xa hoi. ((hieu va) or (hieu qua)) cac toc xa dan dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach y)) 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) OR (sach y)) 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) OR (sach y)) tang xa hoi. ((hieu va) or (hieu qua)) cac toc xa dan dai cua tre*.