Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
ban hang » ngan hang
thuc ban » thuoc ban, thuc dan, thu ban
may thoi » gay thoi, may thi, tay thoi
va tham » van tham, va cham, va thanh
hieu va » lieu va, hieu qua
may hoi » tay hoi, mai hoi, may hmi
ke mang » ke nang, ke trang
sai ke » sai ky
tu sai » tu bai, tu san, tu cai
vi su » ve su, ki su, oi su

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sai ke mang ((may hoi) or (may thoi)). hieu va tham thuc ban hang ((vi su) OR (va su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sai ke mang ((may hoi) OR (may thoi)). hieu va tham thuc ban hang ((vi su) OR (va su)) triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sai ke mang ((may hoi) or (may thoi)). hieu va tham thuc ban hang ((vi su) OR (va su)) triet*".