Perhaps you should try some spelling variations:
dong giao » dung giao, luong giao, thong giao
nang giao » nang cao
thu sach » tu sach, thuat sach, thuoc sach
vien cac » vien bach, vien dai, vien da
sach ky » sac ky, sach y, sach ty
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet
ve cac » va cac
so van » su van, vo van

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