Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh vai » hanh vi, hanh va, hanh tai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va
ky sang » ky nang, ky dang, ky tang
xuc va » duc va, tuc va, luc va
ma hoi » mai hoi, ma hoa, me hoi

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 ky sang ((ma hoi) or (xa hoi)). ((hieu ve) OR (hieu van)) cam xuc va hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang ((ma hoi) OR (xa hoi)). ((hieu ve) OR (hieu van)) cam xuc va hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky sang ((ma hoi) or (xa hoi)). ((hieu ve) OR (hieu van)) cam xuc va hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky sang ((ma hoi) or (xa hoi)). ((hieu ve) OR (hieu van)) cam xuc va hanh vai cua tre*.