Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hieu van » hieu va, thien van, lieu va
thuc dan » thuc hanh, hoc dan, thuc vat
can thuc » dan thuc, van thuc, cay thuc
danh di » danh du, xanh di, danh dien
danh vi » hanh vi, dinh vi, danh va
so sach » so sanh, bo sach, co sach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
van can » van canh, van ban, ban can

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 y ((nang xa) or (nang ma)) hoi. hieu van can thuc dan ((danh vi) OR (danh di)) cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((nang xa) OR (nang ma)) hoi. hieu van can thuc dan ((danh vi) OR (danh di)) cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y ((nang xa) or (nang ma)) hoi. hieu van can thuc dan ((danh vi) OR (danh di)) cua viet".
• Adding a wildcard symbol may retrieve word variants: so sach y ((nang xa) or (nang ma)) hoi. hieu van can thuc dan ((danh vi) OR (danh di)) cua viet*.