Perhaps you should try some spelling variations:
doanh cua » doanh luan
nam thuc » nam thuoc, am thuc, nam thu
thuc day » thuc dan, thuc vat
doanh va » doan va, doanh tai, hanh va
hieu van » hieu va, thien van, lieu va
te sach » toc sach
cua tre » cua te, cuu tre, cua triet
lang xa » lang ha, dang xay, lang van

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 y ((lang xa) or (hang va)) hoi. hieu van nam thuc day ((doanh va) OR (doanh cua)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y ((lang xa) OR (hang va)) hoi. hieu van nam thuc day ((doanh va) OR (doanh cua)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach y ((lang xa) or (hang va)) hoi. hieu van nam thuc day ((doanh va) OR (doanh cua)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach y ((lang xa) or (hang va)) hoi. hieu van nam thuc day ((doanh va) OR (doanh cua)) cua tre*.