Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, tu cach
hieu ve » hieu va, hieu van
cuu tre » cua tre, cau tren, cau treo
te sach » toc sach
ve cac » va cac, vien cac
cac tu » cac thu, cach tu, cac du
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cuu » vi luu, vinh cuu
x hoi » xa hoi, x ho, 5 hoi
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) or (te sach)) ky nang ((x hoi) OR (o hoi)). hieu ve cac tu va dan vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ky nang ((x hoi) OR (o hoi)). hieu ve cac tu va dan vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (te sach)) ky nang ((x hoi) OR (o hoi)). hieu ve cac tu va dan vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) ky nang ((x hoi) OR (o hoi)). hieu ve cac tu va dan vi cuu tre*.