Amazon.com : PhotoTrust 8"×8" (20cmX20cm) Universal Collapsible Round Studio Softbox Flash Diffuser for On Camera or Off Camera Flash Gun Compatible with Nikon SB-500 SB-600 SB-700 SB-800 SB-900 SB-910 Canon Speed :
The Nikon Creative Lighting System: Using the SB-600, SB-800, SB-900, and R1C1 Flashes: Hagen, Mike: 9781933952413: Amazon.com: Books
The Nikon Creative Lighting System, 3rd Edition: Using the SB-500, SB-600, SB-700, SB-800, SB-900, SB-910, and R1C1 Flashes: Hagen, Mike: 9781937538668: Amazon.com: Books
Amazon.com: JJC 2PCS Flash Hot Shoe Cover Cap for X Flash Speedlight SB-600 SB-500 SB-400 SB-300, ABS Flash Shoe Mount Protector with Self-Locking Function : Electronics
Amazon.com : Vello Bounce Dome (Diffuser) for Nikon SB-600 & Olympus FL-36 Speedlights(2 Pack) : Electronics
Nikon Speedlight SB-600: Digital Photography Review