Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
cac ban » cac dan, cac van, can ban
cuc ban » cua ban, cuu ban, duc ban
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
lang xa » lang ha, dang xay, lang van
tang ma » mang may, tang van
anh vi » hanh vi, anh va, anh ve
vi cua » vai cua, di cua
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 ky ((lang xa) or (tang ma)) hoi. hieu va cam ((cuc ban) OR (cac ban)) anh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((lang xa) OR (tang ma)) hoi. hieu va cam ((cuc ban) OR (cac ban)) anh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((lang xa) or (tang ma)) hoi. hieu va cam ((cuc ban) OR (cac ban)) anh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((lang xa) or (tang ma)) hoi. hieu va cam ((cuc ban) OR (cac ban)) anh vi cua tre*.