Perhaps you should try some spelling variations:
dang xay » dang van, van xay
tu sach » thu sach, su sach, te sach
dao van » do van, dang van
dao vai » dao va, dao bai, dao hai
cac tuc » cac toc, cac tu, cac tac
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
dang xa » lang xa, dang ha, dang va
cua tre » cua te, cuu tre, cua triet
tuc va » thuc va, truc va, tuc xa

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 (dang xay)) hoi. hieu va cac tuc va ((dao vai) OR (dao van)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((dang xa) OR (dang xay)) hoi. hieu va cac tuc va ((dao vai) OR (dao van)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((dang xa) or (dang xay)) hoi. hieu va cac tuc va ((dao vai) OR (dao van)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((dang xa) or (dang xay)) hoi. hieu va cac tuc va ((dao vai) OR (dao van)) cua tre*.