Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
vai cua » dai cua, hai cua, lai cua
dao vai » dao van, dao va, dao bai
thuc va » thuc vat, thuc dan, thuc day
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
dang xa » dang xay, lang xa, dang ha
cua tre » cua te, cuu tre, cua triet
tuc va » truc va, tuc xa, duc 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 ty ((dang xa) or (van xay)) hoi. hieu va cac ((tuc va) OR (thuc va)) dao vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((dang xa) OR (van xay)) hoi. hieu va cac ((tuc va) OR (thuc va)) dao vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((dang xa) or (van xay)) hoi. hieu va cac ((tuc va) OR (thuc va)) dao vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((dang xa) or (van xay)) hoi. hieu va cac ((tuc va) OR (thuc va)) dao vai cua tre*.