Perhaps you should try some spelling variations:
danh vai » danh sai, doanh van, dang van
te sach » toc sach
sach ky » sac ky, sach y, sach ty
danh va » doanh va, hanh va, anh va
toc nam » hoc nam, oc nam, goc nam
cac toc » cac toi, cac nuoc, cac thoi
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
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: te sach ky ((nang xa) OR (lang xa)) hoi. hieu va cac toc nam ((danh vai) or (danh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((nang xa) OR (lang xa)) hoi. hieu va cac toc nam ((danh vai) OR (danh va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((nang xa) OR (lang xa)) hoi. hieu va cac toc nam ((danh vai) or (danh va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((nang xa) OR (lang xa)) hoi. hieu va cac toc nam ((danh vai) or (danh va)) cua tre*.