Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
dung hoc » dong hoc, dung thuoc, trung hoc
hieu chi » hieu moi
hieu cac » hieu luc, hieu va, hieu van
nhung ho » nhung hoc, nhung kho, nhung nho
tu sach » su sach, te sach, tu cach
ho quoc » hoc quoc, hop quoc, he quoc
quoc vi » quoc va, quoc ve, quoc viet

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) or (thu sach)) dung hoc ((hieu chi) OR (hieu cac)) cua ets : nhung ho quoc vi đai~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) dung hoc ((hieu chi) OR (hieu cac)) cua ets : nhung ho quoc vi đai.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) dung hoc ((hieu chi) OR (hieu cac)) cua ets : nhung ho quoc vi đai".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) dung hoc ((hieu chi) OR (hieu cac)) cua ets : nhung ho quoc vi đai*.