Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
dang xay » dang van, van xay
doc sach » hoc sach, nuoc sach, dac sac
lang xa » lang ha, lang van
qua cao » qua cac, qua ca, qua cai
va danh » va dinh, va dan, va hanh
danh va » doanh va, hanh va, anh va
va cua » va chua, via cua, ca cua
cua te » cua tu
su va » su van, tu va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) OR (doc sach)) tru ((lang xa) or (dang xay)) hoi. hieu qua cao su va danh va cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) tru ((lang xa) OR (dang xay)) hoi. hieu qua cao su va danh va cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) tru ((lang xa) or (dang xay)) hoi. hieu qua cao su va danh va cua te*".