BrickLink - Part 3622pb040 : LEGO Brick 1 x 3 with White 'POLICE' Bold Narrow Large Font on Blue Background Pattern (Sticker) - Set 4440 [Brick, Decorated] - BrickLink Reference Catalog
LEGO Brick 1x1 with 2 Side-studs (100 pcs) | BRICKshop - LEGO en DUPLO specialist
LEGO® Element Development: the Escalator Link – Interview with Stephan Breum Steen | New Elementary: LEGO® parts, sets and techniques
Sets designed by Steen Sig Andersen | 2019 | Brickset: LEGO set guide and database