Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dang xay » dang van, van xay
thuc van » thuc vat, thuc dan, thuc hanh
xay hoi » xa hoi, tay hoi, cay phoi
hieu ve » hieu va, hieu van
thuc va » thuc vat, thuc dan, thuc day
hai cua » thai cua, hoi cua, lai cua
sach o » sach lo, sac o, sach y
o dang » xo dang, do dang, so dang
ve am » va am

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

• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach o dang xay hoi. hieu ve am ((thuc van) OR (thuc va)) thanh ((hai cua) OR (dai cua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach o dang xay hoi. hieu ve am ((thuc van) OR (thuc va)) thanh ((hai cua) or (dai cua)) tre~".
• Adding a wildcard symbol may retrieve word variants: toc sach o dang xay hoi. hieu ve am ((thuc van) OR (thuc va)) thanh ((hai cua) or (dai cua)) tre*.