Perhaps you should try some spelling variations:
nguoi sach » nguoi san, nuoc sach
toc sach » hoc sach, doc sach, thuoc sach
hang doi » hang di, hang loi, huong doi
doi cuu » doi cua, doi cuoc
va hang » van hang, va nang, va lang
cac thu » cach thuc, cac thoi
cuu tre » cua tre, cau tren, cau treo
hieu va » lieu va
nang xa » nang x, lang xa, nang ma
tu nang » tru nang, tu nong, tu nano
thu va » thuc va, thue va, 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 (nguoi sach)) tu nang xa hoi. ((hieu va) OR (hieu qua)) cac thu va hang doi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (nguoi sach)) tu nang xa hoi. ((hieu va) OR (hieu qua)) cac thu va hang doi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (nguoi sach)) tu nang xa hoi. ((hieu va) OR (hieu qua)) cac thu va hang doi cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (nguoi sach)) tu nang xa hoi. ((hieu va) OR (hieu qua)) cac thu va hang doi cuu tre*.