Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh van » thanh san, thanh toan, thanh phan
cam thuc » nam thuc, cam thu, can thuc
hieu va » lieu va, hieu qua
van cua » vang cua, ban cua, dan cua
cua tre » cua te, cuu tre, cua triet
so sac » so sach, so dac
sac ky » cac ky, sai ky
x hoi » xa hoi, o hoi, 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: so sac ky nang ((x hoi) or (x ho)). hieu va ((cam thuc) OR (am thuc)) ban thanh van cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sac ky nang ((x hoi) OR (x ho)). hieu va ((cam thuc) OR (am thuc)) ban thanh van cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sac ky nang ((x hoi) or (x ho)). hieu va ((cam thuc) OR (am thuc)) ban thanh van cua tre".
• Adding a wildcard symbol may retrieve word variants: so sac ky nang ((x hoi) or (x ho)). hieu va ((cam thuc) OR (am thuc)) ban thanh van cua tre*.