Perhaps you should try some spelling variations:
dinh cong » dinh cuong, dinh hong, dinh long
cong cua » cong cu, dong cua, huong cua
tu sach » thu sach, su sach, te sach
va dinh » van dinh, va kinh, va tinh
cao duc » dao duc, cao suc, giao duc
cac duc » cac du, cac dac, cac nuoc
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
mang xa » lang xa, mang may, dang xay
sang ma » tang ma, nang ma, sang tao
cua tre » cua te, cuu tre, cua triet

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 ((mang xa) or (sang ma)) hoi. hieu va ((cac duc) OR (cao duc)) va dinh cong cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((mang xa) OR (sang ma)) hoi. hieu va ((cac duc) OR (cao duc)) va dinh cong cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((mang xa) or (sang ma)) hoi. hieu va ((cac duc) OR (cao duc)) va dinh cong cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((mang xa) or (sang ma)) hoi. hieu va ((cac duc) OR (cao duc)) va dinh cong cua tre*.