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Social media
Pixel
Social Icons
Digg
DarkGray
16x16
Mighty Social Icons
SteelBlue
32x32
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WPZOOM Social Networking Icon Set
RoyalBlue
38x38
Macchiato
Sm, Digg
20x20
32 Pixel Social Media Icons
Teal
Classy Social Media Icons
Social Networking
Social Media Mini
Dead simple
15x15