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