19. • NASA, PROVENPARTNERS, TNT en (helaas) enkele niet meer te achterhalen bronnen.
En onder de betreffende creative commons licentie:
• Tonz (http://www.flickr.com/photos/tonz)
• Larsz (http://www.flickr.com/photos/criminalintent/)
• hans s (http://www.flickr.com/photos/archeon/)
• Estherase (http://www.flickr.com/photos/estherase/)
• Sweatrash (http://www.flickr.com/photos/kevin_trahar/)
• steven n fettig (http://www.flickr.com/photos/stevenfettig/)
• Paul Mayne (http://www.flickr.com/photos/paulm/)
• Berbercarpet (http://www.flickr.com/photos/flickerbulb/)
• Xflickrx (http://www.flickr.com/photos/environment/)
Afbeeldingen met dank aan