Perhaps you should try some spelling variations:
ban hanh » ban hang
ky tang » ky nang, ky dang, kho tang
cham so » cham soc, cham o, cham hoi
hieu va » lieu va, hieu qua
mai hoi » mai khoi, dai hoi, lai hoi
cua tre » cua te, cuu tre, cua triet
ham so » nam so, cham soc
ma hoi » xa hoi, ma hoa, me hoi
vi cua » vai cua, di cua

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: tu cac ky tang ((ma hoi) OR (mai hoi)). hieu va ((cham so) OR (ham so)) ban hanh vi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu cac ky tang ((ma hoi) or (mai hoi)). hieu va ((cham so) OR (ham so)) ban hanh vi cua tre~".
• Adding a wildcard symbol may retrieve word variants: tu cac ky tang ((ma hoi) or (mai hoi)). hieu va ((cham so) OR (ham so)) ban hanh vi cua tre*.