Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam tu
ca viet » va viet, co viet, hoa viet
ky sang » ky nang, ky dang, ky tang
sang ma » tang ma, nang ma, sang tao
hang di » hang doi, hang vi, hang dien
hieu le » hieu ve, hieu he, hieu ly
hanh di » hanh vi, hanh de, danh di
su sac » su sach, su cac, su xac
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: su sac ky sang ma hoi. hieu le ((nam thuc) OR (nam thu)) vat ((hanh di) or (hang di)) ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sac ky sang ma hoi. hieu le ((nam thuc) OR (nam thu)) vat ((hanh di) OR (hang di)) ca viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sac ky sang ma hoi. hieu le ((nam thuc) OR (nam thu)) vat ((hanh di) or (hang di)) ca viet*".