Perhaps you should try some spelling variations:
toc cach » hoc cach, toc sach, truoc cach
van hanh » van thanh, ban hanh, van anh
pham huu » pham duc, pham duy, phan huy
cach tu » cach thuc
hieu ve » hieu va, hieu van
nang xa » lang xa, nang ma, mang xa
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 cach tu ((nang xa) OR (nang x)) 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 cach tu ((nang xa) OR (nang x)) 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 cach tu ((nang xa) OR (nang x)) hoi. hieu ve ((chao xu) or (pham huu)) van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: toc cach tu ((nang xa) OR (nang x)) hoi. hieu ve ((chao xu) or (pham huu)) van hanh vi cua tre*.