Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
te sach » toc sach
sach ly » sach y, sach lo, sach ty
ly nang » ky nang, ly hang, ly vang
hieu ve » hieu va, hieu van
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet
me hoi » le hoi
ve cac » va cac, vien cac
cac lo » cac lop, cac co, cac bo
lo van » le van, vo van, so van

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 ly nang ((me hoi) or (ma hoa)). hieu ve cac lo van hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ly nang ((me hoi) OR (ma hoa)). hieu ve cac lo van hanh tai cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach ly nang ((me hoi) or (ma hoa)). hieu ve cac lo van hanh tai cua tre*.