Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
cam tuc » cam xuc, nam thuc, dam thuc
sach ty » sach y, sach tu, sach thu
tu sach » thu sach, su sach, te sach
hieu ve » hieu van
cao hoi » cau hoi, co hoi, cao hoc
ty nang » ky nang, ty xang, ty hang
hieu va » lieu va, hieu qua
cam tu » cam thu, nam tu, dam tu
va dan » ca dan, va dao, va dau
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: tu sach ty nang cao hoi. ((hieu ve) or (hieu va)) ((cam tuc) OR (cam tu)) va dan ca cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang cao hoi. ((hieu ve) OR (hieu va)) ((cam tuc) OR (cam tu)) va dan ca cau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang cao hoi. ((hieu ve) or (hieu va)) ((cam tuc) OR (cam tu)) va dan ca cau tren*".