Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
tru nang » tra nang, tri nang, truc nano
va hanh » van hanh, va thanh, va danh
truc va » thuc va, thuc vat, trung va
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
va cao » va co, va dao, va bao
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: ((toc sach) or (hoc sach)) tru nang xa hoi. hieu ((va cao) OR (va cac)) truc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) tru nang xa hoi. hieu ((va cao) OR (va cac)) truc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) tru nang xa hoi. hieu ((va cao) OR (va cac)) truc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) tru nang xa hoi. hieu ((va cao) OR (va cac)) truc va hanh vi cua tre*.