This internet site uses pictures of the following photographer, stock agencies, sources:
freeimages.com, Flickr, Wikipedia
Source: rmorijn / 123RF Standard-Bild
Source: Usiminas
Source: Usiminas
Source: Usiminas
Source: www.freeimages.com
http://de.freeimages.com/photo/modern-office-building-1186276
Photographer: balu-ertl
Source: www.freeimages.com
http://www.freeimages.com/photo/364796
Photographer: Luis Lopez (luisete)