Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
cua viet » ca viet, cua vat, cua dieu
sang mai » sang ma, sang tai, lang mai
so sach » so sanh, bo sach, co sach
tinh vi » trinh vi, tinh voi, tinh va
va tinh » may tinh
thuc va » thuc vat, thuc dan, thuc day
hieu ly » hieu ky, lieu ly, dieu ly
sach ky » sac ky, sach y, sach ty
hieu le » hieu ve, hieu he, tieu le
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang

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

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