Perhaps you should try some spelling variations:
nhanh thai » nhanh thi, nhanh thanh, nhanh thang
hieu van » hieu va, thien van, lieu va
thai cua » than cua, tai cuc, tri cua
dang xa » dang xay, dang ha, dang va
lang xa » lang ha, dang xay, lang van
van cam » van nam, van lam, van cau
duc van » duc tan, duc manh, duc phan
cua tre » cua te, cuu tre, cua triet
su hai » su tai
hai ky » thai ky, hoi ky, hai ly

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 (lang xa)) hoi. hieu van cam ((duc van) or (duc va)) nhanh thai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su hai ky ((dang xa) OR (lang xa)) hoi. hieu van cam ((duc van) OR (duc va)) nhanh thai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su hai ky ((dang xa) OR (lang xa)) hoi. hieu van cam ((duc van) or (duc va)) nhanh thai cua tre".
• Adding a wildcard symbol may retrieve word variants: su hai ky ((dang xa) OR (lang xa)) hoi. hieu van cam ((duc van) or (duc va)) nhanh thai cua tre*.