Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
cai viet » mai viet, tai viet, ca viet
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
ky sang » ky nang, ky dang, ky tang
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
hanh va » hang va, hanh vi
va nam » van nam, ha nam, va nay
va cai » va cac, va bai, va dai

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky sang ((mai hoi) or (ma hoa)). hieu va nam thuc va hanh va cai viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky sang ((mai hoi) OR (ma hoa)). hieu va nam thuc va hanh va cai viet.
• Adding a wildcard symbol may retrieve word variants: su sach ky sang ((mai hoi) or (ma hoa)). hieu va nam thuc va hanh va cai viet*.