Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
khoa toc » hoa toc, khoa thuoc, khoa quoc
khoa hoc » hoa hoc
hieu chi » hieu cac, hieu moi
nhung bo » nhung bi, nhung bai, nhung don
chi cua » chi cuc, khi cua, cuoi cua
hon vi » chon vi, hon ai, hon va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ((khoa toc) or (khoa hoc)) hieu chi cua ets : nhung bo ((hon vi) OR (don vi)) đai~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ((khoa toc) OR (khoa hoc)) hieu chi cua ets : nhung bo ((hon vi) OR (don vi)) đai.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ((khoa toc) or (khoa hoc)) hieu chi cua ets : nhung bo ((hon vi) OR (don vi)) đai".
• Adding a wildcard symbol may retrieve word variants: hoc sach ((khoa toc) or (khoa hoc)) hieu chi cua ets : nhung bo ((hon vi) OR (don vi)) đai*.