Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
cau thuc » cau truc, cuu thuc, can thuc
van cua » vang cua, ban cua, dan cua
va dinh » van dinh, va kinh, va tinh
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, tu cach
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
te sach » toc sach
cua te » cua tu

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 (te sach)) ky tang xa hoi. ((hieu van) OR (hieu va)) cau thuc va dinh van cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ky tang xa hoi. ((hieu van) OR (hieu va)) cau thuc va dinh van cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (te sach)) ky tang xa hoi. ((hieu van) OR (hieu va)) cau thuc va dinh van cua te".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) ky tang xa hoi. ((hieu van) OR (hieu va)) cau thuc va dinh van cua te*.