Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hieu van » thien van, hieu ve
so sach » so sanh, bo sach, co sach
cao hoi » cau hoi, co hoi, cao hoc
hanh vu » hanh vi, hanh va, hanh tu
hieu va » hieu qua
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
vu cua » hu cua, tu cua
cua tu » cua tuc, cua su, cua cu
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang

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 cao hoi. ((((hieu van) OR (hieu va))) or (lieu va)) nam thuc va hanh vu cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach v nang cao hoi. ((((hieu van) OR (hieu va))) OR (lieu va)) nam thuc va hanh vu cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach v nang cao hoi. ((((hieu van) OR (hieu va))) or (lieu va)) nam thuc va hanh vu cua tu".
• Adding a wildcard symbol may retrieve word variants: so sach v nang cao hoi. ((((hieu van) OR (hieu va))) or (lieu va)) nam thuc va hanh vu cua tu*.