Robles, G. (2013). Sketchbook Pro digital painting essentials. Packt Publishing.
Chicago-viite (17. p.)Robles, Gil. Sketchbook Pro Digital Painting Essentials. Birmingham: Packt Publishing, 2013.
MLA-viite (9. p.)Robles, Gil. Sketchbook Pro Digital Painting Essentials. Packt Publishing, 2013.
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