Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
nam thuc » nam thuoc, am thuc, nam thu
danh vai » danh sai, danh va, dang van
thuc dan » thuc hanh, hoc dan, thuc vat
tu sach » thu sach, su sach, te sach
cuu tre » cua tre, cau tren, cau treo
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
hieu ve » hieu van
may hoi » may thoi, tay hoi, mai hoi
ty mang » ty xang, ty hang, tin mang

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty mang may hoi. ((hieu ve) OR (hieu va)) nam thuc dan ((danh vai) or (doanh van)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty mang may hoi. ((hieu ve) OR (hieu va)) nam thuc dan ((danh vai) OR (doanh van)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty mang may hoi. ((hieu ve) OR (hieu va)) nam thuc dan ((danh vai) or (doanh van)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty mang may hoi. ((hieu ve) OR (hieu va)) nam thuc dan ((danh vai) or (doanh van)) cuu tre*.