Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
nang dai » nang dau, nang tai, lang dai
tai cua » thai cua, tai cuc, tri cua
luc van » luoc van, luu van, duc van
cua tre » cua te, cuu tre, cua triet
sach ty » sach tu, sach thu, xach tay
va cao » va cac, va co, va dao
va cam » va cham, va cac, va cai

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach y) OR (sach ty)) nang dai hoc. hieu ((va cam) OR (va cao)) luc van hanh tai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach y) or (sach ty)) nang dai hoc. hieu ((va cam) OR (va cao)) luc van hanh tai cua tre~".
• Adding a wildcard symbol may retrieve word variants: su ((sach y) or (sach ty)) nang dai hoc. hieu ((va cam) OR (va cao)) luc van hanh tai cua tre*.