Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, thanh san
tu sach » thu sach, su sach, te sach
cam duc » cam xuc, cao duc, pham duc
hieu va » lieu va, hieu qua
sach ty » sach y, sach tu, sach thu
lang xa » lang ha, dang xay, lang van
tang ma » mang may, tang van
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cao

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 ty ((tang ma) or (lang xa)) hoi. hieu va cam duc va ((thanh tai) OR (doanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((tang ma) OR (lang xa)) hoi. hieu va cam duc va ((thanh tai) OR (doanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((tang ma) or (lang xa)) hoi. hieu va cam duc va ((thanh tai) OR (doanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((tang ma) or (lang xa)) hoi. hieu va cam duc va ((thanh tai) OR (doanh tai)) cua tre*.