Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
pham huu » pham duc, pham duy, phan huy
van hanh » van thanh, ban hanh, van anh
doc sach » hoc sach, nuoc sach, dac sac
tru nang » tra nang, tri nang, truc nano
hieu ve » hieu va, hieu van
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
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 (doc sach)) tru nang xa hoi. hieu ve ((chao xu) or (pham huu)) van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) tru nang xa hoi. hieu ve ((chao xu) OR (pham huu)) van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) tru nang xa hoi. hieu ve ((chao xu) or (pham huu)) van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) tru nang xa hoi. hieu ve ((chao xu) or (pham huu)) van hanh vi cua tre*.