Perhaps you should try some spelling variations:
hanh thanh » nhanh thanh, thanh thanh, khanh thanh
van hanh » van thanh, ban hanh, van anh
thanh cu » thanh chu, thanh tu, thanh ca
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
cu tren » tu tren, dua tren
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
ve cac » va cac, vien cac
o hoi » co hoi, o hoc, o hoa
o hai » co hai, so hai, o lai

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang ((o hoi) OR (o hai)). hieu ve cac duc van hanh thanh cu tren~.
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang ((o hoi) or (o hai)). hieu ve cac duc van hanh thanh cu tren*.