Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
va thanh » gia thanh, va tinh, le thanh
qua cac » cua cac
hai cua » thai cua, dai cua, hoi cua
cac duc » cac du, cao duc, cac dac
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
sang xa » song xa, lang xa, sang ma
sai ky » sac ky
tu sai » tu bai, tu san, tu cai

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

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