Sources of images:
All images are free/open icons distributed by Sourceforge and available as a package form Open Icon Library, an archive created by Jeff Israel (http://openiconlibrary.sourceforge.net/). 
They are free to use for commercial or non-commercial and royalty-free.
License available at http://creativecommons.org/licenses/GPL/2.0/ Source GNOME-Colors

Descriptions of licenses for each image used:

Source Crystal Project URL: http://everaldo.com/crystal/
view-refresh-2.png
dialog-ok-2.png
user-group-new.png
view-calendar-todo.png
tools-wizard.png
document-properties.png
kdmconfig-2.png
xclock-2.png
help-2.png

Source Tango Icon Library URL http://tango.freedesktop.org/Tango_Icon_Library
address-bool-new-2.png
emblem-notice.png
dialog-no-2.png
view-refresh-4.png renamed view-refresh-2.png


Source Oxygen Icons URL http://www.oxygen-icons.org
document-encrypt-3.png
feed-subscribe.png
mail-reply-list.png
view-history.png
accessories-dictionary-2.png
preferences-desktop-text-to-speech.png
system-help-3.png
format-text-direction-ltr-2.png
format-text-direction-rtl-2.png

Source echo-icon-theme URL https://fedorahosted.org/echo-icon-theme/
document-open-2.png
system-log-out.png
applications-office.png

Source Crystal Clear URL http://commons.wikimedia.org/wiki/Crystal_Clear
edit-find-9.png

Source GNOME Icon Theme URL http://art.gnome.org/
edit-find-and-replace.png
accessories-text-editor-3.png
camera-web.png
document-save-2.png
zoom-in-3.png
zoom-out-3.png
edit-delete-2.png
call-start.png
call-stop.png

Source_URL http://code.google.com/p/gnome-colors/
archive-insert-2.png

Source Tango harm-on-icons URL http://gnome-look.org/content/show.php/Tango+mine?content=76316
emblem-what.png
folder-user.png

Source Warthan's Stuff: Sovereign State Flags of the World  URL http://warthan.org/nation_flags.html
flag-de.png
flag-es.png
flag-fr.png
flag-gb.png

Source Wikimedia Commons URL http://commons.wikimedia.org/wiki/Main_Page file:///mnt/ogre/privy/docs/icons/open_icon_library-devel/icons/wiki_commons_GPL/tmp/KeePassX.svg
keepassx.png

source Nuvola URL http://www.icon-king.com/projects/nuvola/
education-edutainment-2.png
systemm-settings.png

Source nuoveXT URL http://nuovext.pwsp.net
edit-undi-8.png renamed retour.png

Source Nuvola http://www.icon-king.com/projects/nuvola/
accessories-text-editor-6.png
arts-2.png

source software ImageMagick 6.3.7 08/07/09 Q16 http://www.imagemagick.org
ProjectManager.app.png

Source Intrigue Icon Set URL http://simpleinnovation.net/index.php?page=22&source=2&id=2
printer.png