Perhaps you should try some spelling variations:
doanh dan » doanh ban, doanh van, doanh dao
hieu van » hieu va, thien van, lieu va
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang xa » lang xa, nang ma, mang xa
van lam » van nam
duoc va » nuoc va, duoc ma, duong va
dan cua » dan ca, ban cua, dai cua
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky ((nang xa) OR (nang x)) hoi. hieu van lam ((duoc va) or (duc va)) doanh dan cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((nang xa) OR (nang x)) hoi. hieu van lam ((duoc va) OR (duc va)) doanh dan cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((nang xa) OR (nang x)) hoi. hieu van lam ((duoc va) or (duc va)) doanh dan cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((nang xa) OR (nang x)) hoi. hieu van lam ((duoc va) or (duc va)) doanh dan cua tre*.