Perhaps you should try some spelling variations:
day danh » day manh, dai danh, dao danh
thuc day » thuc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
vai cua » dai cua, hai cua, lai cua
tu sach » thu sach, su sach, te sach
va nam » van nam, ha nam, va nay
vai ca » vai cac, bai ca, vai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach y ((nang ma) or (nang x)) hoi. hieu va nam thuc day danh ((vai ca) OR (vai cua)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang ma) OR (nang x)) hoi. hieu va nam thuc day danh ((vai ca) OR (vai cua)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((nang ma) or (nang x)) hoi. hieu va nam thuc day danh ((vai ca) OR (vai cua)) tren".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang ma) or (nang x)) hoi. hieu va nam thuc day danh ((vai ca) OR (vai cua)) tren*.