BrickLink - Part 3437pe1 : LEGO Duplo, Brick 2 x 2 with Black and White Eye with Spot Pattern on Opposite Sides [Duplo, Brick, Decorated] - BrickLink Reference Catalog
File:2 duplo lego bricks.jpg - Wikimedia Commons
LEGO® DUPLO® Creative Brick Set - 45019
Lego Duplo ALPHABET LETTER R Replacement 2 x 2 x 2 BLOCK Building Brick Part | eBay