Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van ban
so sach » so sanh, bo sach, co sach
tai cua » thai cua, tai cuc, tri cua
van anh » van thanh, tuan anh, van minh
kham oc » kham cuoc
vu kham » vu khanh
hieu vu » hieu va, hieu ve, hieu su
sach ty » sach y, sach tu, sach thu
lang ha » long ha
nang ma » tang ma, sang ma, nang cao
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 ty ((nang ma) 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 ty ((nang ma) OR (lang ha)) hoi. hieu vu kham oc ((van hanh) OR (van anh)) tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty ((nang ma) 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 ty ((nang ma) or (lang ha)) hoi. hieu vu kham oc ((van hanh) OR (van anh)) tai cua tre*.