Perhaps you should try some spelling variations:
cham sac » cham soc, pham sach, cap sac
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
so sach » so sanh, bo sach, co sach
hieu va » lieu va, hieu qua
hieu ve » hieu van
lang xa » lang ha, dang xay, lang van
cua tre » cua te, cuu tre, cua triet
y lang » o lang, _ lang, tay lang
di cua » dai cua, doi cua, de 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 y lang xa hoi. ((hieu ve) OR (hieu va)) cham sac ((van hanh) or (ban hanh)) di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y lang xa hoi. ((hieu ve) OR (hieu va)) cham sac ((van hanh) OR (ban hanh)) di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y lang xa hoi. ((hieu ve) OR (hieu va)) cham sac ((van hanh) or (ban hanh)) di cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach y lang xa hoi. ((hieu ve) OR (hieu va)) cham sac ((van hanh) or (ban hanh)) di cua tre*.