Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
thu sac » thu sach, thu san, thu xac
nang xa » nang x, lang xa, nang ma
hieu va » lieu va
cac lao » ca lao, cac loai, cac giao
va hanh » va thanh, va danh, ban hanh
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sac ky nang xa hoi. ((hieu va) or (hieu qua)) cac lao ((va hanh) OR (van hanh)) hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sac ky nang xa hoi. ((hieu va) OR (hieu qua)) cac lao ((va hanh) OR (van hanh)) hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sac ky nang xa hoi. ((hieu va) or (hieu qua)) cac lao ((va hanh) OR (van hanh)) hai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sac ky nang xa hoi. ((hieu va) or (hieu qua)) cac lao ((va hanh) OR (van hanh)) hai cua tre*.