Perhaps you should try some spelling variations:
cac thoi » cac toi, cac hop, cac tro
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
cac thu » cach thuc
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
ly hang » ly quang
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 ((ky nang) or (ly hang)) xa hoi. hieu ve ((cac thu) OR (cac thoi)) va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky nang) OR (ly hang)) xa hoi. hieu ve ((cac thu) OR (cac thoi)) va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky nang) or (ly hang)) xa hoi. hieu ve ((cac thu) OR (cac thoi)) va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky nang) or (ly hang)) xa hoi. hieu ve ((cac thu) OR (cac thoi)) va hanh vi cua tre*.