Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
va tham » van tham, va thanh, va thuat
va cham » va chat
mai hoi » mai khoi, dai hoi, lai hoi
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
ma hoi » xa hoi, ma hoa, me hoi
soc va » hoc va, loc va, doc 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: tu sach y nang ((ma hoi) or (mai hoi)). lieu ((va cham) OR (va tham)) soc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((ma hoi) OR (mai hoi)). lieu ((va cham) OR (va tham)) soc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((ma hoi) or (mai hoi)). lieu ((va cham) OR (va tham)) soc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((ma hoi) or (mai hoi)). lieu ((va cham) OR (va tham)) soc va hanh vi cua tre*.