Perhaps you should try some spelling variations:
ban thanh » ban hanh
ban hang » ngan hang
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu va » hieu qua
cam dua » ca dua, cay dua, chay dua
san cua » sang cua, ban cua, dan cua
cua tre » cua te, cuu tre, cua triet

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 xa hoi. ((hieu va) or (lieu va)) cam dua ((ban thanh) or (ban hang)) san cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang xa hoi. ((hieu va) OR (lieu va)) cam dua ((ban thanh) OR (ban hang)) san cua tre.
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang xa hoi. ((hieu va) or (lieu va)) cam dua ((ban thanh) or (ban hang)) san cua tre*.