Tip: where to get the periodic table of the chemical elements

My favorite official source to download printable copies of the periodic table of the chemical elements (also known in the post-USSR countries as the Mendeleev's table) is IUPAC (the International Union of Pure and Applied Chemistry):

• IUPAC Periodic Table of the Elements

(Currently, the table on the IUPAC site dates back to 2016-11-28).

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Last updated: 2017-02-11

TestDisk & PhotoRec: nice tools to recover lost partitions & files

TestDisk + PhotoRec is a nice toolset to recover lost disk partitions (or at least rescue some files from corrupted filesystems) in case of storage media failures, re-partitioning errors etc.
Works for disk images too.
More to say, it's a free & open source (GPL v2+) cross-platform (Linux, *BSD, Apple Mac OS X, Oracle / Sun Solaris, MS-DOS, MS Windows) software.

Presently, in Debian-based Linux distros, TestDisk & PhotoRec have been packaged into a single testdisk package, so you can install both tools at once:

# apt-get install testdisk