Perhaps you should try some spelling variations:
hanh thai » nhanh thai, hinh thai, anh thai
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
cac duc » cac du, cao duc, cac dac
van cac » van hac, van cau, van bac
cua tre » cua te, cuu tre, cua triet
dang ha » dong ha, dung ha, lang ha
dang xa » dang xay, lang xa, dang va
hai ky » thai ky, hoi ky, hai ly
su hai » su tai

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

• Performing a fuzzy search may retrieve terms with similar spellings: su hai ky ((dang xa) or (dang ha)) hoi. hieu van cac duc tan ((hanh thai) or (hanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su hai ky ((dang xa) OR (dang ha)) hoi. hieu van cac duc tan ((hanh thai) OR (hanh tai)) cua tre.
• Adding a wildcard symbol may retrieve word variants: su hai ky ((dang xa) or (dang ha)) hoi. hieu van cac duc tan ((hanh thai) or (hanh tai)) cua tre*.