Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
sach ty » sach y, sach tu, xach tay
cua tre » cua te, cuu tre, cua triet
xang xa » lang xa, mang xa, ang xa
nay tu » tay tu, may tu
dan vi » doan vi, don vi, gan vi
dan va » doan va, dan ca, ban va
va nay » va ngay, va cay

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

• Performing a fuzzy search may retrieve terms with similar spellings: co ((sach ty) or (sach thu)) xang xa hoi. lieu va nay tu va ((dan vi) OR (dan va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: co ((sach ty) OR (sach thu)) xang xa hoi. lieu va nay tu va ((dan vi) OR (dan va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "co ((sach ty) or (sach thu)) xang xa hoi. lieu va nay tu va ((dan vi) OR (dan va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: co ((sach ty) or (sach thu)) xang xa hoi. lieu va nay tu va ((dan vi) OR (dan va)) cua tre*.