Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
ban hanh » ban hang
thuc ban » thuoc ban, thuc dan, thu ban
nang may » mang may, nang ma, bang may
hieu va » lieu va
may hoi » may thoi, tay hoi, mai hoi
vai cua » dai cua, lai cua, bai cua
hai cua » thai cua, dai cua, hoi cua
sac ky » cac ky, sai ky
tu sac » tu sach, tu cac, tu san

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky nang may hoi. ((hieu va) OR (hieu qua)) tham thuc ban hanh ((vai cua) or (hai cua)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang may hoi. ((hieu va) OR (hieu qua)) tham thuc ban hanh ((vai cua) OR (hai cua)) viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky nang may hoi. ((hieu va) OR (hieu qua)) tham thuc ban hanh ((vai cua) or (hai cua)) viet".
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang may hoi. ((hieu va) OR (hieu qua)) tham thuc ban hanh ((vai cua) or (hai cua)) viet*.