Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
day thanh » dao thanh, dat thanh, da thanh
khach ky » hanh ky, thanh ky
day manh » van manh, duc manh, ha manh
vu khach » vu khanh, vu khac, vay khach
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua
o hoi » co hoi, o hoc, o hai
x hoi » xa 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 khach ky nang ((x hoi) or (o hoi)). hieu ve cham thuc ((day thanh) or (day manh)) di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu khach ky nang ((x hoi) OR (o hoi)). hieu ve cham thuc ((day thanh) OR (day manh)) di cua tre.
• Adding a wildcard symbol may retrieve word variants: vu khach ky nang ((x hoi) or (o hoi)). hieu ve cham thuc ((day thanh) or (day manh)) di cua tre*.