Perhaps you should try some spelling variations:
bang hang » ban hang, hang hang, nang hang
hoc bang » hoc bong, hoc tang, hoc dan
te sach » toc sach
sach ky » sac ky, sach y, sach ty
va cham » va chat, va tham
ve cham » ve chat, vu cham, ve chim
dai hoi » dai hoc, dai hai, dai moi
mai doi » moi doi, mai hoi, mai khoi
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua

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 ky nang ((mai doi) or (dai hoi)). hieu ((ve cham) OR (va cham)) hoc bang hang va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang ((mai doi) OR (dai hoi)). hieu ((ve cham) OR (va cham)) hoc bang hang va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang ((mai doi) or (dai hoi)). hieu ((ve cham) OR (va cham)) hoc bang hang va cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang ((mai doi) or (dai hoi)). hieu ((ve cham) OR (va cham)) hoc bang hang va cua tre*.