BrickLink - Part BA059pb01 : LEGO Stickered Assembly 6 x 2 x 3 with '8421 Heavy Loader' and Red and White Danger Stripes Pattern (Sticker) - Set 8421 - 3 Brick 2 x 6 [Stickered Assembly] - BrickLink Reference Catalog
BrickLink - Set 8421-1 : LEGO Mobile Crane [Technic:Model:Construction] - BrickLink Reference Catalog
BrickLink - Set 8421-1 : LEGO Mobile Crane [Technic:Model:Construction] - BrickLink Reference Catalog
LEGO MOC Telescopic Handler 8421 MOC by brickmark | Rebrickable - Build with LEGO
Comparing 8053 the 8421 Cranes - LEGO Technic, Model Team and Scale Modeling - Eurobricks Forums
Mobile Crane Collection (8053, 42009, 42108) : Lego, The Lego Group, Consumer Discretionary Sector : r/legotechnic