Perhaps you should try some spelling variations:
sach thue » sach thieu, sach tham, cach thuc
sach thu » sach thieu, sach tham, cach thuc
thanh va » thanh van, hanh va, thanh ha
nam duoc » nam thuoc, dat duoc, nam moc
hieu van » hieu va, thien van, lieu va
da duoc » tao duoc, hoa duoc
cua tre » cua te, cuu tre, cua triet
ang xa » lang xa, mang xa, dang xay
va cua » va chua, via cua, ca cua

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 thu) OR (sach thue)) ang xa hoi. hieu van ((nam duoc) or (da duoc)) gia thanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach thu) OR (sach thue)) ang xa hoi. hieu van ((nam duoc) OR (da duoc)) gia thanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((sach thu) OR (sach thue)) ang xa hoi. hieu van ((nam duoc) or (da duoc)) gia thanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: toc ((sach thu) OR (sach thue)) ang xa hoi. hieu van ((nam duoc) or (da duoc)) gia thanh va cua tre*.