CS5 is no longer sold through regular reseller channels.
Grazie Peter, quindi devo per forza acquistare la CC?
You may be able to find CS5 through aftermarket resellers who buy old stock, or perhaps Amazon but be very careful. You can still buy a perpetual license for CS6 direct from Adobe if you are averse to subscription software, but there will never be any new enhancements for it, and probably no more bug fixes. All new development is focused on new versions (naturally).
Ok! Capisco, non mi fido a comprare fuori da Adobe... ma se acquisto la cs6 o la cc posso poi salvare i file in cs5? O sono poi incompatibili? I miei clienti usano il cs5.
Grazie! sei stato molto gentile e chiaro!
You can save or export as IDML and CS5 should be able to open that, IF it updated fully. There are some caveats, though -- use of any features introduced since CS5 will be lost, and text will probably reflow, changing some line endings, because the text engines have evolved.
This is generally not considered a good workflow for collaboration.