Perhaps you should try some spelling variations:
ban hang » ngan hang
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
vai cua » dai cua, hai cua, lai cua
hieu va » lieu va
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
cam tu » cam thu, nam tu, dam tu
tu ban » thu ban, te ban
di cua » dai cua, doi cua, de cua

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 dang xa hoi. ((hieu va) OR (hieu qua)) cam tu ban hang ((vai cua) or (di cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky dang xa hoi. ((hieu va) OR (hieu qua)) cam tu ban hang ((vai cua) OR (di cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky dang xa hoi. ((hieu va) OR (hieu qua)) cam tu ban hang ((vai cua) or (di cua)) tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ky dang xa hoi. ((hieu va) OR (hieu qua)) cam tu ban hang ((vai cua) or (di cua)) tre*.