Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
xanh dai » vanh dai, xanh di, xanh tai
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 » tu sach, thuat sach, thuoc sach
sang ma » tang ma, nang ma, sang tao
hieu va » lieu va, hieu qua
lo sang » lam sang, luc sang, cao sang
te sach » toc sach
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (thu sach)) lo sang ma hoi. ((hieu van) or (hieu va)) nam thuc day xanh dai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (thu sach)) lo sang ma hoi. ((hieu van) OR (hieu va)) nam thuc day xanh dai cua viet.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (thu sach)) lo sang ma hoi. ((hieu van) or (hieu va)) nam thuc day xanh dai cua viet*.