Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
cua viet » ca viet, hoa viet, cua dieu
so sach » so sanh, bo sach, co sach
sach ty » sach y, sach tu, sach thu
ty hang » ly hang, ty xang, thi hang
hieu ve » hieu va, hieu van
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
ma hoi » mai hoi, ma hoa, me hoi
ve nam » he nam, va nam, le nam

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 ty hang ((ma hoi) or (xa hoi)). hieu ve nam thuc va hanh vi ((cua viet) or (cua vat))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty hang ((ma hoi) OR (xa hoi)). hieu ve nam thuc va hanh vi ((cua viet) OR (cua vat)).
• Adding a wildcard symbol may retrieve word variants: so sach ty hang ((ma hoi) or (xa hoi)). hieu ve nam thuc va hanh vi ((cua viet) or (cua vat))*.