Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
ban thanh » ban hanh, ban hang
cua tre » cua te, cuu tre, cua triet
cam duc » cao duc, pham duc, nam duoc
hieu ve » hieu va, hieu van
tang ma » tang van
xac ky » cac ky, sac ky, bac ky
su xac » pu xac, su cac

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