Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
cac thu » cach thuc, cac thoi
cam thu » nam thu, ca thu, cam phu
hieu ve » hieu va, hieu van
su sach » so sach, vu sach
cao hoi » cau hoi, co hoi, cao hoc
te sach » toc sach
ca dan » cac dan, ca dao
ca cau » cua cau, cac cau, can cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (te sach)) ky nang cao hoi. hieu ve ((cam thu) OR (cac thu)) ca dan ca cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (te sach)) ky nang cao hoi. hieu ve ((cam thu) OR (cac thu)) ca dan ca cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (te sach)) ky nang cao hoi. hieu ve ((cam thu) OR (cac thu)) ca dan ca cau tren".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (te sach)) ky nang cao hoi. hieu ve ((cam thu) OR (cac thu)) ca dan ca cau tren*.