Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
tinh vai » tinh va, tinh hai, tinh bai
ban tinh » ban thanh, quan tinh, ban hanh
tu sach » thu sach, su sach, te sach
vai cua » dai cua, hai cua, lai cua
cac cua » cach cua, cac qua, ca cua
cac cuc » cac cuoc, cac nuoc, cac cach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet

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