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- 'Vasco da Gama' Bridge over River 'Tejo' in Lisbon (Horizontal) © Luis Santos
- Marbles © Darren Falkenberg
- abstract blue background © Ayvengo
- Welle-S4 © RalfenByte
- difference and similarity © Konstantin Sutyagin
- surface reflex © zampa
- blue cubes © Dmitry Sunagatov
