Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cua tre » cua te, cuu tre, cua triet
va hanh » va thanh, va danh, ban hanh
sang ma » tang ma, nang ma, sang tao
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
cac loc » cac lop, cac toc, cac hoc
de cua » le cua, te cua, dieu cua
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
ve cac » va cac, vien cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sac ky ((sang ma) or (lang xa)) hoi. hieu ve cac loc ((va hanh) or (van hanh)) de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky ((sang ma) OR (lang xa)) hoi. hieu ve cac loc ((va hanh) OR (van hanh)) de cua tre.
• Adding a wildcard symbol may retrieve word variants: te sac ky ((sang ma) or (lang xa)) hoi. hieu ve cac loc ((va hanh) or (van hanh)) de cua tre*.