Perhaps you should try some spelling variations:
sach thue » sach thieu, sach tham, cach thuc
sach thu » sach thieu, sach tham, cach thuc
xang xa » lang xa, mang xa, ang xa
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
va hoc » van hoc
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach thu) or (sach thue)) xang xa hoi. hieu va hoc (nuoc or quoc) va dan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach thu) OR (sach thue)) xang xa hoi. hieu va hoc (nuoc OR quoc) va dan vi cua tre.
• Adding a wildcard symbol may retrieve word variants: thu ((sach thu) or (sach thue)) xang xa hoi. hieu va hoc (nuoc or quoc) va dan vi cua tre*.