Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van ban
so sach » so sanh, bo sach, co sach
kham oc » kham cuoc
tai cua » thai cua, tai cuc, tri cua
van anh » van thanh, tuan anh, van minh
vu kham » vu khanh
hieu vu » hieu va, hieu ve, hieu su
lang ha » long ha
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y ((nang cao) or (lang ha)) hoi. hieu vu kham oc ((van hanh) or (van anh)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((nang cao) OR (lang ha)) hoi. hieu vu kham oc ((van hanh) OR (van anh)) tai cua tre.
• Adding a wildcard symbol may retrieve word variants: so sach y ((nang cao) or (lang ha)) hoi. hieu vu kham oc ((van hanh) or (van anh)) tai cua tre*.