Perhaps you should try some spelling variations:
van khanh » van thanh, van hanh, van anh
vu sach » vu bach, su sach, vu khach
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cao
cam tu » cam thu, nam tu, dam tu
vi cua » vai cua, di cua
o hoi » co hoi, o hai, o hoa
o hoc » co hoc, mo hoc, so hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((vu sach) or (van khanh)) ky nang ((o hoi) or (o hoc)). hieu va cam tu va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu sach) OR (van khanh)) ky nang ((o hoi) OR (o hoc)). hieu va cam tu va hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((vu sach) or (van khanh)) ky nang ((o hoi) or (o hoc)). hieu va cam tu va hanh vi cua tre*.