Perhaps you should try some spelling variations:
ban thanh » ban hanh
ban hang » ngan hang
vu sach » vu bach, su sach, vu khach
doi cua » dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
cam duc » cam xuc, cao duc, pham duc
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
long ha » dong ha, cong ha, dong hoa
va cam » va cham, va cac, va cao

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 ty ((nang x) or (long ha)) hoi. hieu va cam duc ((ban thanh) OR (ban hang)) doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ty ((nang x) OR (long ha)) hoi. hieu va cam duc ((ban thanh) OR (ban hang)) doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ty ((nang x) or (long ha)) hoi. hieu va cam duc ((ban thanh) OR (ban hang)) doi cua tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ty ((nang x) or (long ha)) hoi. hieu va cam duc ((ban thanh) OR (ban hang)) doi cua tre*.