Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh doi » thanh loi, thanh moi, thanh do
hieu van » hieu va, thien van
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va
cau hoc » cau hoi, cau hoa, cao hoc
hoc ban » hoc bang, hoc dan, hoc bai
doi cua » dai cua, hoi 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: tu sach ky nang xa hoi. ((((hieu ve) OR (hieu van))) or (lieu va)) cau hoc ban thanh doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang xa hoi. ((((hieu ve) OR (hieu van))) OR (lieu va)) cau hoc ban thanh doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. ((((hieu ve) OR (hieu van))) or (lieu va)) cau hoc ban thanh doi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. ((((hieu ve) OR (hieu van))) or (lieu va)) cau hoc ban thanh doi cua tre*.