Perhaps you should try some spelling variations:
hanh dai » hanh tai, hanh dao, vanh dai
doc hoi » duoc hoi, hoc hoi, doi hoi
doc hai » hoc hai, duc hai, do hai
hieu ve » hieu va, hieu van
cam luc » cam xuc, cau luc
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
can ky » dan ky, ban ky, tan ky
ve cam » ve cham, ve cac, va cam
luc va » duc va, tuc va, loc va

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

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