Perhaps you should try some spelling variations:
hanh doi » thanh doi, hanh noi, hang doi
van hanh » van thanh, ban hanh, van anh
te sach » toc sach
doi cua » dai cua, hoi cua
van bac » van ban, van bao, van hac
sach ty » sach y, sach tu, sach thu
van cac » van hac, van cau, dan cac
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
co dai » co dan, do dai
so van » su van, vo van
co hai » co hoi, o hai, so hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty nang ((co hai) OR (co dai)). hieu ((van cac) or (van bac)) so van hanh doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty nang ((co hai) OR (co dai)). hieu ((van cac) OR (van bac)) so van hanh doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty nang ((co hai) OR (co dai)). hieu ((van cac) or (van bac)) so van hanh doi cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ty nang ((co hai) OR (co dai)). hieu ((van cac) or (van bac)) so van hanh doi cua tre*.