Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
te sach » toc sach
va hanh » van hanh, va thanh, va danh
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, va cam, ve cai
ve cac » va cac, vien cac
vi cua » vai cua, di cua

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

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