Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
sach ky » sac ky, sach y, sach ty
cac cau » cac mau, bac cau, ca cau
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
cam tuc » cam tu, nam thuc, dam thuc
cao hoi » cau hoi, co hoi, cao hoc
va dan » va dao, va dau, va dap
ca dan » cac dan, ca dao

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