Perhaps you should try some spelling variations:
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
cac toc » cac toi, cac nuoc, cac thoi
qua cac » cua cac
cua tre » cua te, cuu tre, cua triet
nang xa » lang xa, nang ma, mang xa
so sanh » do sanh
toc va » hoc va, toc ta, tuc va
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: ((su sach) or (so sanh)) va ((nang xa) OR (nang x)) hoi. hieu qua cac toc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sanh)) va ((nang xa) OR (nang x)) hoi. hieu qua cac toc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sanh)) va ((nang xa) OR (nang x)) hoi. hieu qua cac toc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sanh)) va ((nang xa) OR (nang x)) hoi. hieu qua cac toc va hanh vi cua tre*.