Tango icon theme 0.8.9 by Tango Desktop Project (http://tango.freedesktop.org/Tango_Desktop_Project).
The color palette is public domain. The icon theme is also available as public domain since the 0.8.90 release.

Extensions:

1) mail-send icon (scalable + 32x32 + 22x22 + 16x16 png images) from wikimedia: https://commons.wikimedia.org/wiki/File:Send-email.svg
License: Creative Commons Attribution-Share Alike 3.0 Unported
Copyright: RRZE - https://commons.wikimedia.org/wiki/User:RRZEicons

2) checkbox icon (32x32 + 22x22 + 16x16 png images) - custom icon
License: GPL v.3
Copyright: Dmitry Ivanov

3) format-list-ordered (32x32 + 22x22 + 16x16 png images) - custom icon
License: GPL v.3
Copyright: Dmitry Ivanov

4) format-list-unordered (32x32 + 22x22 + 16x16 png images) - custom icon
License: GPL v.3
Copyright: Dmitry Ivanov

5) tools-check-spelling icon (32x32 + 22x22 + 16x16 png images) from Farm-fresh icon theme: https://www.iconfinder.com/iconsets/fatcow
License: Creative Commons (Attribution 3.0 United States)
Copyright: FatCow Web Hosting

6) insert-horizontal-rule (32x32 + 22x22 + 16x16 png images) - custom icon
License: GPL v.3
Copyright: Dmitry Ivanov

7) format-text-color (32x32 + 22x22 + 16x16 png images) - custom icon
License: GPL v.3
Copyright: Dmitry Ivanov

8) fill-color (32x32 + 22x22 + 16x16 png images) from PixeloPhilia icon theme: https://www.iconfinder.com/iconsets/pixelo
License: Creative Commons (Attribution 3.0 Unported)
Copyright: Ömer Çetin - https://omercetin.deviantart.com

9) insert-table icon (32x32 + 22x22 + 16x16 png images) from Farm-fresh icon theme: https://www.iconfinder.com/iconsets/fatcow
License: Creative Commons (Attribution 3.0 United States)
Copyright: FatCow Web Hosting

10) application-pdf icon (32x32 + 22x22 + 16x16 png images) from Farm-fresh icon theme: https://www.iconfinder.com/iconsets/fatcow
License: Creative Commons (Attribution 3.0 United States)
Copyright: FatCow Web Hosting

11) application-enex (32x32 + 22x22 + 16x16 png images + svg icon) - custom icon based on tango's text-x-generic-template icon
License: GPL v.3
Copyright: Dmitry Ivanov
