Perhaps you should try some spelling variations:
thien van » thi van
thanh hoi » thanh hoai, thanh hoa, thanh hai
hieu van » hieu va, lieu va, hieu ve
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
duc ban » duc tan, dua ban, duc man
duc van » duc va, duc tan, duc manh
hoi cua » hoi chuc
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 van) or (thien van)) cam ((duc ban) OR (duc van)) thanh hoi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang xa hoi. ((hieu van) OR (thien van)) cam ((duc ban) OR (duc van)) thanh hoi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. ((hieu van) or (thien van)) cam ((duc ban) OR (duc van)) thanh hoi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. ((hieu van) or (thien van)) cam ((duc ban) OR (duc van)) thanh hoi cua tre*.