Perhaps you should try some spelling variations:
tham thuc » pham thuc, tam thuc, thai thuc
nham thuc » nhan thuc, nam thuc, nham thu
ban hanh » ban hang
nang ma » tang ma, sang ma, nang cao
hai cua » thai cua, dai cua, hoi cua
hieu va » lieu va, hieu qua
vai cua » dai cua, lai cua, bai cua
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
ma hoi » mai hoi, xa hoi, ma hoa

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 ma hoi. hieu va ((tham thuc) or (nham 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 ma hoi. hieu va ((tham thuc) OR (nham thuc)) ban hanh ((vai cua) OR (hai cua)) viet.
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang ma hoi. hieu va ((tham thuc) or (nham thuc)) ban hanh ((vai cua) or (hai cua)) viet*.