Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
chat cua » nhat cua, chat va, chat huu
sach tu » cach tu, sach ty, sach uu
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach tu) OR (sach thu)) nang ma hoa. hieu va cac duc ((va hanh) or (va danh)) chat cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach tu) OR (sach thu)) nang ma hoa. hieu va cac duc ((va hanh) OR (va danh)) chat cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach tu) OR (sach thu)) nang ma hoa. hieu va cac duc ((va hanh) or (va danh)) chat cua vat".
• Adding a wildcard symbol may retrieve word variants: su ((sach tu) OR (sach thu)) nang ma hoa. hieu va cac duc ((va hanh) or (va danh)) chat cua vat*.