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