Perhaps you should try some spelling variations:
doanh dan » doanh ban, doanh van, doanh dao
hieu van » hieu va, thien van, lieu va
van cac » van hac, van cau, van bac
dan cua » dan ca, ban cua, dai cua
lang xa » lang ha, dang xay, lang van
toc va » toc ta, tuc va, loc va
sac ky » cac ky
cua te » cua tu

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: te ((sac ky) OR (sai ky)) lang xa hoi. hieu van cac ((toc va) OR (hoc va)) doanh dan cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sac ky) or (sai ky)) lang xa hoi. hieu van cac ((toc va) OR (hoc va)) doanh dan cua te~".
• Adding a wildcard symbol may retrieve word variants: te ((sac ky) or (sai ky)) lang xa hoi. hieu van cac ((toc va) OR (hoc va)) doanh dan cua te*.