Best Buy: Panasonic LUMIX G LEICA VARIO-ELMAR 100-400mm F/4.0-6.3 Telephoto Zoom Lens for Mirrorless Micro Four Thirds Compatible Cameras Black H-RS100400
Panasonic Leica 100-400mm Photography Review VS Panasonic 100-300 - YouTube
Real World Comparison of Lumix 100-300 vs 100-400mm Lens – Camera and a Canvas
The Panasonic 100-400mm f/4-6.3 review – A surprisingly good performer!