Perhaps you should try some spelling variations:
hang vai » hang tai, hang hai, hang vi
sach ky » sac ky, sach y, sach kem
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
ve cac » va cac, vien cac
du ban » dua ban, duc ban, du bao
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ky) OR (sach ty)) nang o hoi. hieu ve cac du ban ((hang vai) or (hang va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach ty)) nang o hoi. hieu ve cac du ban ((hang vai) OR (hang va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sach ty)) nang o hoi. hieu ve cac du ban ((hang vai) or (hang va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sach ty)) nang o hoi. hieu ve cac du ban ((hang vai) or (hang va)) cua tre*.