Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
cham luc » cham soc, nhan luc, cham cuu
cua tre » cua te, cuu tre, cua triet
va cham » va chat, va tham
tai cua » thai cua, tai cuc, tri cua
tang ha » tang ma, trung ha, tang van
luc van » luoc van, luu van, duc van
lang ha » long ha
hieu va » lieu va, hieu qua
bai ky » sai ky, bac ky, dai ky
ban ky » van ky, dan ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: te ((bai ky) or (ban ky)) ((tang ha) OR (lang ha)) hoi. hieu va cham luc van hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((bai ky) OR (ban ky)) ((tang ha) OR (lang ha)) hoi. hieu va cham luc van hanh tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((bai ky) or (ban ky)) ((tang ha) OR (lang ha)) hoi. hieu va cham luc van hanh tai cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((bai ky) or (ban ky)) ((tang ha) OR (lang ha)) hoi. hieu va cham luc van hanh tai cua tre*.