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
hieu ve » hieu va, hieu van
duc ban » duc tan, duc van, dua ban
cac duc » cac du, cao duc, cac dac
ve cac » va cac, vien cac
sac ky » cac ky

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

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