Perhaps you should try some spelling variations:
doanh ban » doanh bat, doanh van, doanh nhan
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
xa doanh » va doanh, hoa doanh, van doanh
tay lang » tai lang, tay tang, tay quang
hieu van » hieu va, thien van, lieu va
ban cua » ban quan
cac tuc » cac toc, cac tu, cac tac
van cac » van hac, van cau, van bac
ty lang » ty xang, ty hang, tu lang
cua tre » cua te, cuu tre, cua triet

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ((ty lang) OR (tay lang)) xa hoi. hieu van cac tuc xa doanh ban cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) ((ty lang) or (tay lang)) xa hoi. hieu van cac tuc xa doanh ban cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) ((ty lang) or (tay lang)) xa hoi. hieu van cac tuc xa doanh ban cua tre*.