Perhaps you should try some spelling variations:
chat thom » chat thai, chat hoa, chat cho
chat hoc » chat hoa, cho hoc, vat hoc
sach ky » sac ky, sach y, sach ty
can cau » van cau, ban cau, cac cau
cam tuc » cam xuc, cam tu, nam thuc
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, va dao, va dau
ca cau » cua cau, cac cau, ca cac
ve cam » ve cham, ve cac, va cam

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