Quellenangaben für die verwendeten Bilder und Grafiken:

© blas – Fotolia.com
© contrastwerkstatt - Fotolia.com
© Namphuong Van, unsplash.com
© Stairs by flashcurd
© Mountain by Gordon Tarpley
© Frankfurt skyrise ©jelwolf Fotolia.com
© Pixelbliss – Fotolia.com
© Amir Kaljikovic – Fotolia.com
© contrastwerkstatt – Fotolia.com
© Mopic – Fotolia.com
© Stauke – Fotolia.com
© lumen-digital – Fotolia.com
© Picture-Factory – Fotolia.com
© pressmaster – Fotolia.com
© xy – Fotolia.com
© Kzenon – Fotolia.com
© michaeljung – Fotolia.com
© Kadmy – Fotolia.com
© pojoslaw – Fotolia.com
© Jonathan Stutz – Fotolia.com
© rico287 – Fotolia.com
© Unclesam – Fotolia.com
© Heiko Barth – Fotolia.com
© dispicture – Fotolia.com
© dly – Fotolia.com
© lassedesignen – Fotolia.com
© ferkelraggae – Fotolia.com
© by-studio – Fotolia.com
© Benicce – Fotolia.com
© Yuri Arcurs – Fotolia.com
© serdar akbulut – Fotolia.com
© aleksey kashin – Fotolia.com
© hati – Fotolia.com
© Günter Menzl – Fotolia.com
© xin wang – Fotolia.com
© .shock – Fotolia.com
© Kurhan – Fotolia.com
© Jonas Glaubitz – Fotolia.com
© Butch – Fotolia.com
© Maksim Shebeko – Fotolia.com
© Anna Reich – Fotolia.com
© micha_h – Fotolia.com
© Gudellaphoto – Fotolia.com
© Sergey Nvns – Fotolia.com
© auremar – Fotolia.com
© images.fix – Fotolia.com
© Magnus – Fotolia.com
© Netfalls – Fotolia.com
© Luftbildfotograf – Fotolia.com
© Diana Valujeva – Fotolia.com
© Africa Studio – Fotolia.com

© iStockphoto.com/dmbaker
© iStockphoto.com/kali9
© iStockphoto.com/adventtr
© iStockphoto.com/hidesy
© iStockphoto.com/shironosov
© iStockphoto.com/kenhurst
© iStockphoto.com/junial
© iStockphoto.com/stuartpitkin
© iStockphoto.com/matthiashass
© iStockphoto.com/Maica
© iStockphoto.com/mediaphotos
© iStockphoto.com/Yuri_Arcurs
© iStockphoto.com/jjayo
© iStockphoto.com/creativepictures
© iStockphoto.com/theboone
© iStockphoto.com/mills21
© iStockphoto.com/abzee
© iStockphoto.com/kzenon
© iStockphoto.com/agenziavisione
© iStockphoto.com/lisegagne
© iStockphoto.com/fabervisum
© iStockphoto.com/mandfredxy
© iStockphoto.com/jgroup
© iStockphoto.com/Cimmerian
© iStockphoto.com/jsmith
© iStockphoto.com/onurdongel
© iStockphoto.com/Daft_Lion_Studio
© iStockphoto.com/ausinasia
© iStockphoto.com/bradwieland
© iStockphoto.com/Entienou
© iStockphoto.com/AtnoYdur
© iStockphoto.com/pictafolio
© iStockphoto.com/deliormanli
© iStockphoto.com/webphotographeer
© iStockphoto.com/Wibofoto
© iStockphoto.com/Bet_Noire
© iStockphoto.com/AlexRaths
© iStockphoto.com/Evgeny_D
© iStockphoto.com/skynesher
© iStockphoto.com/STEEX
© iStockphoto.com/mayo5
© iStockphoto.com/Cybernesco
© iStockphoto.com/fotostorm
© iStockphoto.com/sidewaydesign
© iStockphoto.com/marekuliasz
© iStockphoto.com/Floortje
© iStockphoto.com/fotosipsak
© iStockphoto.com/Ratstuben
© iStockphoto.com/DaveBolton
© iStockphoto.com/marcoscisetti
© iStockphoto.com/Razvan
© iStockphoto.com/aldra
© iStockphoto.com/izusek
© iStockphoto.com/marekuliasz
© iStockphoto.com/AnthiaCumming
© iStockphoto.com/ValentynVolkov
© iStockphoto.com/tomazl
© iStockphoto.com/AVTG
© iStockphoto.com/TPopova
© iStockphoto.com/Adventure_Photo
© iStockphoto.com/urbancow
© iStockphoto.com/ssuni
© iStockphoto.com/Spiderstock
© iStockphoto.com/gehringj
© iStockphoto.com/aluxum
© iStockphoto.com/caracterdesign
© iStockphoto.com/KLH49
© iStockphoto.com/Hafizov
© iStockphoto.com/nyul
© iStockphoto.com/jgfoto
© iStockphoto.com/rotofrank
© iStockphoto.com/mato70
© iStockphoto.com/carlosphotos
© iStockphoto.com/SamBurt
© iStockphoto.com/narvikk
© iStockphoto.com/johnnyscriv
© iStockphoto.com/zoomstudio
© iStockphoto.com/Antagain
© iStockphoto.com/P_Wei
© iStockphoto.com/Marcin Rychly
© iStockphoto.com/Brian McEntire
© iStockphoto.com/Hanquan Chen
© iStockphoto.com/dagmar heymans
© iStockphoto.com/Daniel Kourey
© iStockphoto.com/Antagain
© iStockphoto.com/Daniel Kourey
© iStockphoto.com/Cristian Lazzari
© iStockphoto.com/Robert Milek
© iStockphoto.com/Mikhail Basov
© iStockphoto.com/Svetlana Shapiro
© iStockphoto.com/gemphotography