Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
ban tinh » ban thanh, quan tinh, ban hanh
cham cuc » cham cuu, pham cuc, pham chuc
tinh vi » trinh vi, tinh voi, tinh va
cuc ban » cua ban, cac ban, cuu ban
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
te sach » toc sach
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: ((thu sach) or (te sach)) ky dang xa hoi. ((hieu ve) OR (hieu van)) cham cuc ban tinh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (te sach)) ky dang xa hoi. ((hieu ve) OR (hieu van)) cham cuc ban tinh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (te sach)) ky dang xa hoi. ((hieu ve) OR (hieu van)) cham cuc ban tinh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (te sach)) ky dang xa hoi. ((hieu ve) OR (hieu van)) cham cuc ban tinh vi cua tre*.