Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
so sach » so sanh, bo sach, co sach
sach ty » sach y, sach tu, sach thu
lang ha » long ha
hieu vu » hieu va, hieu ve, hieu su
vu kham » vu khanh
kham oc » kham cuoc
tai cua » thai cua, tri cua, dai cua
oc van » hoc van, luoc van, quoc van

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 cao) or (lang ha)) hoi. hieu vu kham oc van hanh ((tai cua) OR (tai cuc)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty ((nang cao) OR (lang ha)) hoi. hieu vu kham oc van hanh ((tai cua) OR (tai cuc)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty ((nang cao) or (lang ha)) hoi. hieu vu kham oc van hanh ((tai cua) OR (tai cuc)) tre".
• Adding a wildcard symbol may retrieve word variants: so sach ty ((nang cao) or (lang ha)) hoi. hieu vu kham oc van hanh ((tai cua) OR (tai cuc)) tre*.