Perhaps you should try some spelling variations:
sach ky » sac ky, sach y, sach ty
mat cua » ma cua, manh cua, mang cua
vat cua » bat cua, dat cua, hat cua
cac tac » cac toc, cac bac, cac dac
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
tang ma » mang may, tang van
tang xa » trang xa, lang xa, tang ha
tac va » tac da, tac xa, tuc 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 ((tang xa) OR (tang ma)) hoi. hieu va cac tac va van ((vat cua) or (mat cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((tang xa) OR (tang ma)) hoi. hieu va cac tac va van ((vat cua) OR (mat cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((tang xa) OR (tang ma)) hoi. hieu va cac tac va van ((vat cua) or (mat cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((tang xa) OR (tang ma)) hoi. hieu va cac tac va van ((vat cua) or (mat cua)) tre*.