Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
day xanh » day manh, cay xanh, day danh
thuc day » thuc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
hieu van » thien van, lieu va, hieu ve
thu sach » thuat sach, thuoc sach, thu hoach
sang ma » tang ma, nang ma, sang tao
lo sang » lam sang, luc sang, cao sang
hieu va » lieu va, hieu qua
xanh di » danh di, vanh dai, xanh tai
tu sach » su sach, te sach, tu cach
ma hoi » mai hoi, xa hoi, ma hoa
di cua » dai cua, doi cua, de cua

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) OR (thu sach)) lo sang ma hoi. ((hieu van) or (hieu va)) nam thuc day xanh di cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) lo sang ma hoi. ((hieu van) OR (hieu va)) nam thuc day xanh di cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) lo sang ma hoi. ((hieu van) or (hieu va)) nam thuc day xanh di cua viet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) lo sang ma hoi. ((hieu van) or (hieu va)) nam thuc day xanh di cua viet*.