The icon is based on the Edu App icon as published under:

https://www.ethz.ch/content/associates/services/de/lehre/lehrbetrieb/it-services-lehrbetrieb/lehrunterstuetzende-applikationen/eduapp-service.html

Additionally the Oxygen-Icons for application-pdf and application-vnd.ms-excel
were used.

See licenses/README.txt for details about the license.

Sources:
 http://download.kde.org/stable/4.14.1/src/oxygen-icons-4.14.1.tar.xz

Tools: Debian Package: inkscape Version: 0.48.3.1-1.3
 Debian Package: imagemagick Version: 8:6.7.7.10-5+deb7u3
 Debian Package: icnsutils Version 0.8.1-1
 Debian Pacakge: gimp

The pngs were created with inkscape bitmap export.
The ico file was created with inkscape convert:
for file in *.svgz; do
    pngname=$(echo $file |sed 's/\.svgz/\.png/')
    iconame=$(echo $file |sed 's/\.svgz/\.ico/')
    convert 256_$pngname 128_$pngname 64_$pngname 48_$pngname 32_$pngname 22_$pngname 16_$pngname \
            $iconame
done;

The Macos icon was created with:
png2icns icon.icons 16_icon.png 32_icon.png 48_icon.png 128_icon.png 256_icon.png