Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
thuc ban » thuoc ban, thuc dan, thu ban
cua viet » ca viet, cua vat, cua dieu
ban hanh » ban hang
hieu va » lieu va, hieu qua
may hoi » may thoi, tay hoi, mai hoi
va tham » van tham, va cham, va thanh
sac ky » cac ky

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