Perhaps you should try some spelling variations:
ban hang » ngan hang
nang mai » nang ma, nang tai, lang mai
cam thuc » am thuc, nam thuc, cam thu
thuc ban » thuoc ban, thuc dan, thu ban
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu van
vai cua » dai cua, hai cua, lai cua
hieu va » lieu va, hieu qua
di cua » dai cua, doi cua, de cua
so sac » so sach, so dac
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sac ky nang mai hoi. ((hieu ve) OR (hieu va)) cam thuc ban hang ((vai cua) or (di cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sac ky nang mai hoi. ((hieu ve) OR (hieu va)) cam thuc ban hang ((vai cua) OR (di cua)) tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sac ky nang mai hoi. ((hieu ve) OR (hieu va)) cam thuc ban hang ((vai cua) or (di cua)) tre*".