Sigma 70-300mm F4-5.6 DG Macro Overview: Digital Photography Review
Sigma 100-300mm f/4 DG EX HSM : Specifications and Opinions | JuzaPhoto
Sigma 300mm F4 Macro APO A-mount lens info
Amazon.com : Sigma 70-300mm F/4-5.6 DG OS SLD Super Multi-Layer Coated Telephoto Lens for Canon AF Mount Digital SLR Cameras : Camera Lenses : Electronics
Sigma APO 70-300mm f/4-5.6 DG Macro Lens for Sony A 508205 B&H