Perhaps you should try some spelling variations:
van doanh » toan doanh, van dong, van thanh
doanh va » doan va, doanh tai, doanh cua
sach thu » sach thue, sach thieu, sach tham
cuu tre » cua tre, cau tren, cau treo
cau luu » cau luc
sang xa » song xa, lang xa, sang ma
hieu ve » hieu van
luu van » cuu van, luan van, luu hanh
hieu va » lieu va, hieu qua
va cuu » va cau, va chu, va huu
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sac ky) or (sach thu)) sang xa hoi. ((hieu ve) or (hieu va)) cau luu van doanh va cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sac ky) OR (sach thu)) sang xa hoi. ((hieu ve) OR (hieu va)) cau luu van doanh va cuu tre.
• Adding a wildcard symbol may retrieve word variants: su ((sac ky) or (sach thu)) sang xa hoi. ((hieu ve) or (hieu va)) cau luu van doanh va cuu tre*.