Fonts: SourceSansPro, SIL OFL (see SIL-OFL.txt)

Backgrounds: www.publicdomainpictures.net, Public Domain
b_0.jpg - Petr Kratochvil
b_1.jpg - George Hodan
b_2.jpg - Petr Kratochvil
b_3.jpg - George Hodan

Images: from Wikipedia, all images where cropped to be square
p_cobra.jpg - Pavan Kumar N, CC-By-SA 3.0
p_lion.jpg - Kevin Pluck, CC-By 2.0
p_tiger.jpg - Monika Betley, GFDL
p_swan.jpg - Mindaugas Urbonas, CC-By-SA 2.5
p_brownbear.jpg - Jean-noël Lafargue, FAL
p_icebear.jpg - Andreas Weith, CC BY-SA 4.0
p_seagull.jpg - David Menke, PD
p_shark.jpg - Terry Goss, CC-By 2.5
p_orca.jpg - Robert Pittman, PD
p_horse.jpg - Dietmar Rabich, CC BY-SA 4.0
p_zebra.jpg - Bernard DUPONT, CC-By-SA 2.0
p_fox.jpg - I. Malene, CC-By 2.5
p_badger.jpg - BadgerHero, CC-By-SA 3.0
p_lama.jpg - Anakin, CC-By-SA 3.0
p_wolf.jpg - Malene Thyssen, CC-By-SA 3.0
p_owl.jpg - Mdf, CC-By-SA 3.0
p_dolphin.jpg - NASA, PD
p_squirrel.jpg - Diliff, CC-By-SA 3.0
p_colibri - Mdf, CC-By-SA 3.0
p_elephant.jpg - Ikiwaner, GFDL 1.2
p_cat.jpg - Basile Morin, CC-By-SA 4.0
p_penguin.jpg - Ben Tubby, CC-By 2.0
p_koala.jpg - Diliff, CC-By-SA 3.0
p_rhino.jpg - Ikiwaner, GFDL 1.2
p_germansheperd.jpg - Flaurentine, CC-By-SA 3.0
p_deer.jpg - Scott Bauer, PD
p_sheep.jpg - Nevit Dilmen, CC-By-SA 3.0
p_giraffe.jpg - John Walker, PD
p_rabbit.jpg - JJ Harrison, CC-By-SA 3.0
p_eagle.jpg - AngMoKio, CC-By-SA 2.5
p_hippo.jpg - Derek Keats, CC-By 2.0
p_cow.jpg - Daniel Schwen, CC-By-SA 3.0
p_ginueapig.jpg - Jg4817, CC-By-SA 3.0
p_gorilla.jpg - Brocken Inaglory, CC-By-SA 3.0
p_parrot.jpg - Benjamint444, GFDL 1.2
p_goat.jpg - fir0002, GFDL 1.2
c_front/back/focus.png - PD, based on a PD stone texture by Daniel Smith

Sounds: all PD

Links to licenses:
https://creativecommons.org/publicdomain/mark/1.0/
https://creativecommons.org/licenses/by/2.0/
https://creativecommons.org/licenses/by-sa/2.0/
https://www.gnu.org/licenses/fdl.html
http://artlibre.org/licence/lal/en/

