Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
sach thu » sach thue, sach thieu, sach tham
hieu van » thien van, lieu va, hieu ve
bang va » hang va, ban va, trang va
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
vat dan » va dan, van dan, vat ran
dan sai » danh sai, doan sai, dan tai
sai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach thu ((bang va) or (lang xa)) hoi. ((hieu van) OR (hieu va)) am thuc vat dan sai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach thu ((bang va) OR (lang xa)) hoi. ((hieu van) OR (hieu va)) am thuc vat dan sai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach thu ((bang va) or (lang xa)) hoi. ((hieu van) OR (hieu va)) am thuc vat dan sai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach thu ((bang va) or (lang xa)) hoi. ((hieu van) OR (hieu va)) am thuc vat dan sai cua tre*.