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

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 (lai hoi)). hieu va nam thuc va hanh vi ((ca viet) or (so viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky sang ((mai hoi) OR (lai hoi)). hieu va nam thuc va hanh vi ((ca viet) OR (so viet)).
• Adding a wildcard symbol may retrieve word variants: su sach ky sang ((mai hoi) or (lai hoi)). hieu va nam thuc va hanh vi ((ca viet) or (so viet))*.