Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
te sach » toc sach
sach ty » sach y, sach tu, sach thu
ty hang » ly hang, ty xang, thi hang
hang co » hang cho, hang ca, nang co
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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 ty hang co hoc. ((hieu van) OR (hieu va)) cau truc ((ban hanh) or (van hanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty hang co hoc. ((hieu van) OR (hieu va)) cau truc ((ban hanh) OR (van hanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty hang co hoc. ((hieu van) OR (hieu va)) cau truc ((ban hanh) or (van hanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ty hang co hoc. ((hieu van) OR (hieu va)) cau truc ((ban hanh) or (van hanh)) vi cua tre*.