Perhaps you should try some spelling variations:
thanh va » thanh van, hanh va, thanh ha
duoc ban » duc ban, quoc ban, buoc ban
cua tre » cua te, cuu tre, cua triet
doc ban » do ban, doi ban, duc ban
ve chat » va chat, van chat
hieu ve » hieu va, hieu van
may hoi » may thoi, tay hoi, mai hoi
sach ty » sach y, sach tu, sach thu
sac ky » cac ky, sai ky
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 ((sac ky) or (sach ty)) mang may hoi. hieu ve chat ((doc ban) OR (duoc ban)) thanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sac ky) OR (sach ty)) mang may hoi. hieu ve chat ((doc ban) OR (duoc ban)) thanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sac ky) or (sach ty)) mang may hoi. hieu ve chat ((doc ban) OR (duoc ban)) thanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sac ky) or (sach ty)) mang may hoi. hieu ve chat ((doc ban) OR (duoc ban)) thanh va cua tre*.