Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
nhung don » nhung van, nhung bo
thu sach » tu sach, thuat sach, thu hoach
dieu cac » dieu can, hieu cac, dien cac
khoa hoc » hoa hoc
dieu cao » dieu can, dieu cam, dieu co
don so » dong so, hon so, con so
so vat » so van

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 (thuoc sach)) khoa hoc ((dieu cao) OR (dieu cac)) cua ets : nhung don so vat đai~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuoc sach)) khoa hoc ((dieu cao) OR (dieu cac)) cua ets : nhung don so vat đai.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (thuoc sach)) khoa hoc ((dieu cao) OR (dieu cac)) cua ets : nhung don so vat đai".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuoc sach)) khoa hoc ((dieu cao) OR (dieu cac)) cua ets : nhung don so vat đai*.