Where do I find older Ubuntu versions (specifically 11.10)

Due to compatibility issues I am looking for an older Ubuntu version. Where can I download Onceiric Ocelot? I found this page

http://old-releases.ubuntu.com/releases/

But this only goes up to Maverick.

You can Download it here

http://releases.ubuntu.com/oneiric/

Select the appropriate File.

if compatibility is issue then Try Lubuntu or Xubuntu 12.04.

The Old Ubuntu Releases webpage has been updated so that it includes all the old releases of Ubuntu starting from Ubuntu 4.10. Some old releases of Kubuntu, Edubuntu, and Xubuntu are also available here.

Current to May, 2018 Old Ubuntu Releases includes the latest old Ubuntu release, which is currently Ubuntu 17.04.