Perhaps you should try some spelling variations:
hang vai » hang tai, hang hai, hang vi
vien cac » vien bach, vien dai, vien da
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
ve cac » va cac
du ban » dua ban, duc ban, du bao
nang o » nang co, nang ho, nang ro
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 nang o hoi. hieu ((ve cac) OR (vien 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 nang o hoi. hieu ((ve cac) OR (vien 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 nang o hoi. hieu ((ve cac) OR (vien cac)) du ban ((hang vai) or (hang va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang o hoi. hieu ((ve cac) OR (vien cac)) du ban ((hang vai) or (hang va)) cua tre*.