Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thu nang » thi nang, thu hang, thu bang
xa hanh » xa thanh, xa khanh, va hanh
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, nang ma
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 (toc sach)) thu nang xa hoi. hieu ((ve cam) or (ve cac)) tuc xa hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) thu nang xa hoi. hieu ((ve cam) OR (ve cac)) tuc xa hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) thu nang xa hoi. hieu ((ve cam) or (ve cac)) tuc xa hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) thu nang xa hoi. hieu ((ve cam) or (ve cac)) tuc xa hanh vi cua tre*.