Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh dat » thanh san, thanh hai, thanh van
cua tre » cua te, cuu tre, cua triet
cao duc » dao duc, cao suc, giao duc
ky tang » ky nang, ky dang, kho tang
dat cua » dai cua, day cua, mat cua
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
cam duc » cam xuc, pham duc, nam duoc
su xac » pu xac, su cac
xac ky » cac ky, sac ky, bac ky
ma hoi » xa hoi, ma hoa, me hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: su xac ky tang ((ma hoi) or (mai hoi)). hieu ve ((cam duc) OR (cao duc)) ban thanh dat cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su xac ky tang ((ma hoi) OR (mai hoi)). hieu ve ((cam duc) OR (cao duc)) ban thanh dat cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su xac ky tang ((ma hoi) or (mai hoi)). hieu ve ((cam duc) OR (cao duc)) ban thanh dat cua tre".
• Adding a wildcard symbol may retrieve word variants: su xac ky tang ((ma hoi) or (mai hoi)). hieu ve ((cam duc) OR (cao duc)) ban thanh dat cua tre*.