refcard

Screenshots of the two-page Debian Reference Card:

There are a couple of different ways to get a copy of this handy document. The package debian-refcard (v. 9.0.4) is available from the Stretch (Stable) repos, but it isn't the most up-to-date version of the document. Once installed, it can be found at /usr/share/doc/debian-refcard/refcard-en-a4.pdf.gz/refcard-en-a4.pdf. When I open up this document, I see:

Debian GNU/Linux Reference Card
Version 9.0 - Debian 9 'Stretch' - 2016-07-09

Alternatively, one can click on the "Debian GNU/Linux Reference Card" link at https://www.debian.org/doc/ to download the refcard document, or download the latest refcard.en.pdf document from https://www.debian.org/doc/manuals/refcard/. When I open the refcard.en.pdf document I downloaded, I see:

Debian Reference Card
Version 10.0 - Debian 10 'Buster' -- 2017-07-14

That more up-to-date version appears to be the same one currently found in the Testing and sid repos.