Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh dai » thanh hai, thanh tai, thanh dat
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, hieu van
cau hoc » cau hoi, cau hoa, cao hoc
hoc ban » hoc bang, hoc dan, hoc bai
cua tre » cuu tre, cua triet, dua tren
cua te » cua tu

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 (lieu va)) cau hoc ban thanh dai ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang xa hoi. ((hieu ve) OR (lieu va)) cau hoc ban thanh dai ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. ((hieu ve) or (lieu va)) cau hoc ban thanh dai ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. ((hieu ve) or (lieu va)) cau hoc ban thanh dai ((cua tre) OR (cua te))*.