Perhaps you should try some spelling variations:
dnang giao » dang giao, dung giao, dong giao
nang giao » nang cao
thu sach » tu sach, thuat sach, thuoc sach
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
ky danh » ky anh
ky dang » ky nang
ve cac » va cac, vien cac
so van » su van, vo van
cac so » cac co, cac bo, cac ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ((ky dang) OR (ky danh)) xa hoi. hieu ve cac so van ((dnang giao) or (nang giao)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((ky dang) OR (ky danh)) xa hoi. hieu ve cac so van ((dnang giao) OR (nang giao)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ((ky dang) OR (ky danh)) xa hoi. hieu ve cac so van ((dnang giao) or (nang giao)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ((ky dang) OR (ky danh)) xa hoi. hieu ve cac so van ((dnang giao) or (nang giao)) cua tre*.