Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh hai » thanh phan, thanh hoa, thanh san
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
cao duc » dao duc, cao suc, giao duc
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
cam duc » cam xuc, nam duoc, lam duoc
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa

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 ma hoi. hieu van ((((cam duc) OR (pham duc))) or (cao duc)) ban thanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ma hoi. hieu van ((((cam duc) OR (pham duc))) OR (cao duc)) ban thanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ma hoi. hieu van ((((cam duc) OR (pham duc))) or (cao duc)) ban thanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. hieu van ((((cam duc) OR (pham duc))) or (cao duc)) ban thanh hai cua tre*.