delete magazines as per #356
Merge pull request #847 from borgified/delete_magazines

delete magazines as per #356
[en] Removing duplicated link on Parallel Programming section
[en] Sorting Parallel programming section
Add Bootstrap section with book resource.
Merge pull request #851 from levibostian/bootstrap

Add Bootstrap section with book resource.
Add Git -- the simple guide
Add Git - the simple guide
Merge branch 'master' of github.com:holmboe/free-programming-books into holmboe-master
Alphabetizing Git
Merge pull request #853 from ilyar/master

Add Git - the simple guide [ru]
Merge pull request #856 from esparta/master

[en] Cleaning up Parallel Programming section
21'000 !
Isabelle/HOL

Link to current version as described in http://www21.in.tum.de/~nipkow/LNCS2283/
Merge pull request #857 from diekmann/patch-1

Isabelle/HOL
Concrete Semantics - A Proof Assistant Approach
Merge pull request #858 from diekmann/patch-2

Concrete Semantics - A Proof Assistant Approach
[en] Adding book on Open Source section
add angularjs resources
Merge pull request #859 from ngokevin/master

add angularjs resources