Perhaps you should try some spelling variations:
ban thanh » ban hang
hieu van » thien van, lieu va, hieu ve
ban hanh » ban hang
vu sach » vu bach, su sach, vu khach
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
cam qua » cau qua, cac qua, cay qua
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky nang ma hoi. ((hieu van) or (hieu va)) cam qua ((ban thanh) OR (ban hanh)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang ma hoi. ((hieu van) OR (hieu va)) cam qua ((ban thanh) OR (ban hanh)) vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky nang ma hoi. ((hieu van) or (hieu va)) cam qua ((ban thanh) OR (ban hanh)) vai cua tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang ma hoi. ((hieu van) or (hieu va)) cam qua ((ban thanh) OR (ban hanh)) vai cua tre*.