Perhaps you should try some spelling variations:
nam doanh » nam danh, sam doanh, nhap doanh
doc sach » hoc sach, toc sach, nuoc sach
dang xay » dang van, van xay
doanh va » doan va, doanh tai, doanh cua
nuoc nam » ngoc nam, nuoi nam, nuoc nhat
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
chua tre » chua tri, cua tre, chua trieu
sach ty » sach y, sach tu, sach thu
lang xa » lang ha, lang van
hieu va » lieu va, hieu qua
nang xa » nang x, nang ma, mang xa
va chua » vua chua, ca chua, va chu

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ty ((nang xa) or (((lang xa) OR (dang xay)))) hoi. hieu va cac nuoc nam doanh va chua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ty ((nang xa) OR (((lang xa) OR (dang xay)))) hoi. hieu va cac nuoc nam doanh va chua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ty ((nang xa) or (((lang xa) OR (dang xay)))) hoi. hieu va cac nuoc nam doanh va chua tre*".