Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
thu sach » thuat sach, thuoc sach, thu hoach
hieu van » hieu va, thien van, lieu va
cam tuc » cam xuc, cam tu, nam thuc
tu sach » su sach, te sach, tu cach
hieu ve » hieu va
cao hoi » cau hoi, co hoi, cao hoc
tuc va » thuc va, truc va, tuc xa
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) or (thu sach)) ky nang cao hoi. ((hieu ve) OR (hieu van)) cam tuc va dan ca cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang cao hoi. ((hieu ve) OR (hieu van)) cam tuc va dan ca cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ky nang cao hoi. ((hieu ve) OR (hieu van)) cam tuc va dan ca cau tren".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ky nang cao hoi. ((hieu ve) OR (hieu van)) cam tuc va dan ca cau tren*.