Perhaps you should try some spelling variations:
day nhanh » day thanh, duy nhanh, dac nhan
hieu van » hieu va, thien van, lieu va
day hanh » day thanh, dao hanh, day manh
cua tre » cua te, cuu tre, cua triet
bach v » bach van
v nang » va nang, vu nang, van nang
van am » van nam, van lam, van dam
vi cua » vai cua, di cua
x hoi » o hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu bach v nang ((x hoi) or (xa hoi)). hieu van am thuc ((day hanh) or (day nhanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu bach v nang ((x hoi) OR (xa hoi)). hieu van am thuc ((day hanh) OR (day nhanh)) vi cua tre.
• Adding a wildcard symbol may retrieve word variants: vu bach v nang ((x hoi) or (xa hoi)). hieu van am thuc ((day hanh) or (day nhanh)) vi cua tre*.