Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
sach ky » sac ky, sach ty, sach kem
van cua » vang cua, ban cua, dan cua
truc va » thuc va, thuc vat, trung va
hieu ve » hieu va, hieu van
cao hoi » cau hoi, co hoi, cao hoc
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
tuc va » thuc va, tuc xa, duc va

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) OR (sach y)) nang cao hoi. hieu ve cac ((tuc va) or (truc va)) doanh van cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sach y)) nang cao hoi. hieu ve cac ((tuc va) OR (truc va)) doanh van cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ky) OR (sach y)) nang cao hoi. hieu ve cac ((tuc va) or (truc va)) doanh van cua tre*".