Perhaps you should try some spelling variations:
so sach » so sanh, bo sach, co sach
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
hieu ve » hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ty hang » ly hang, ty xang, thi hang
ty nang » ky nang, ty xang, ly nang
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, luc 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: so sach ((ty nang) OR (ty hang)) mai hoi. ((hieu ve) or (hieu va)) cam xuc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ty nang) OR (ty hang)) mai hoi. ((hieu ve) OR (hieu va)) cam xuc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ty nang) OR (ty hang)) mai hoi. ((hieu ve) or (hieu va)) cam xuc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((ty nang) OR (ty hang)) mai hoi. ((hieu ve) or (hieu va)) cam xuc va hanh vi cua tre*.