Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
cam thuc » am thuc, nam thuc, cam thu
thuc dan » thuc hanh, hoc dan, thuc vat
hieu van » thien van, lieu va, hieu ve
danh va » doanh va, hanh va, anh va
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
cua tre » cua te, cuu tre, cua triet

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 ky tang xa hoi. ((hieu van) or (hieu va)) cam thuc dan ((danh va) or (doanh van)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky tang xa hoi. ((hieu van) OR (hieu va)) cam thuc dan ((danh va) OR (doanh van)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky tang xa hoi. ((hieu van) or (hieu va)) cam thuc dan ((danh va) or (doanh van)) cua tre*.