Perhaps you should try some spelling variations:
dien cuc » dien tu, dieu cua, vien cac
dan dien » doan dien, danh dien, dan den
cam thuc » am thuc, nam thuc, cam thu
so sach » so sanh, bo sach, co sach
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu van
va dan » ca dan, va dao, va dau
cuc te » cua te, cuc thue, cuc tieu
sach v » sach va, sach y, sach 2

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 v ((nang xa) OR (nang ma)) hoi. ((hieu ve) or (hieu va)) cam thuc va dan dien cuc te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach v ((nang xa) OR (nang ma)) hoi. ((hieu ve) OR (hieu va)) cam thuc va dan dien cuc te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach v ((nang xa) OR (nang ma)) hoi. ((hieu ve) or (hieu va)) cam thuc va dan dien cuc te".
• Adding a wildcard symbol may retrieve word variants: so sach v ((nang xa) OR (nang ma)) hoi. ((hieu ve) or (hieu va)) cam thuc va dan dien cuc te*.