Perhaps you should try some spelling variations:
dinh viet » ninh viet, danh viet, trinh viet
hieu van » hieu va, thien van, lieu va
viet cua » viec cua, viet ca, viet qua
te sach » toc sach
va dinh » van dinh, va kinh, va tinh
cac duc » cac du, cao duc, cac dac
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va
ty hang » ly hang, ty xang, thi hang
ty nang » ky nang, ty xang, ly nang

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ty nang) OR (ty hang)) xa hoi. ((hieu ve) OR (hieu van)) cac duc va dinh viet cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ty nang) or (ty hang)) xa hoi. ((hieu ve) OR (hieu van)) cac duc va dinh viet cua tre~".
• Adding a wildcard symbol may retrieve word variants: te sach ((ty nang) or (ty hang)) xa hoi. ((hieu ve) OR (hieu van)) cac duc va dinh viet cua tre*.