Perhaps you should try some spelling variations:
khoa thuoc » khong thuoc, khoa hoc, nha thuoc
sach khoa » bach khoa, sach nha, anh khoa
thieu rui » theu rua, thieu cua, thieu tai
hoc sach » hoc sinh, hoc cac, hoc anh
nhung bi » nhung bai, nhung gi
doc vi » hoc vi, don vi, doc va
oc vi » hoc vi

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 thuoc ((thieu rui) or (thieu nhi)) cua ets : nhung bi ((oc vi) OR (doc vi)) đai~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach khoa thuoc ((thieu rui) OR (thieu nhi)) cua ets : nhung bi ((oc vi) OR (doc vi)) đai.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach khoa thuoc ((thieu rui) or (thieu nhi)) cua ets : nhung bi ((oc vi) OR (doc vi)) đai".
• Adding a wildcard symbol may retrieve word variants: hoc sach khoa thuoc ((thieu rui) or (thieu nhi)) cua ets : nhung bi ((oc vi) OR (doc vi)) đai*.