Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nam thuc, nham thu
doanh van » doan van, doanh va, doanh ban
va trang » va trung, va thanh, va thong
dang van » hoang van, hang va
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
ve nham » ve nha, ve cham
va nang » van nang, da nang, cam nang
cuu tre » cua tre, cau tren, cau treo

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

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