Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, thai thuc
doanh van » doan van, doanh va, doanh ban
xa doanh » va doanh, hoa doanh, van doanh
tam thuc » am thuc, nam thuc, dam thuc
tu sach » thu sach, su sach, te sach
van cua » vang cua, ban cua, dan cua
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: tu sach y ((nang xa) or (lang xa)) hoi. hieu va ((tham thuc) OR (tam thuc)) xa doanh van cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang xa) OR (lang xa)) hoi. hieu va ((tham thuc) OR (tam thuc)) xa doanh van cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((nang xa) or (lang xa)) hoi. hieu va ((tham thuc) OR (tam thuc)) xa doanh van cua tre*".