Social circles are groups of socially interconnected people. A Social circle is distinguished from a social pyramid in that there are two perspectives that can be used to describe a social circle: the perspective of an individual who is the locus of a particular group of socially interconnected people; and the aggregate perspective of a group of socially interconnected people, such as cohesive blocks.

Social Circle
Social Circle
Social Circle
Mining User's Real Social Circle in Microblog
Automatic Social Circle Detection Using Multi-View Clustering
Automatic Social Circle Detection Using Multi-View Clustering
The social circle heuristic: Fast and frugal decisions based on small samples
Moving in social circles—social circle membership and performance implications
Moving in social circles—social circle membership and performance implications
Personalized Recommendation Combining User Interest and Social Circle
Simulating large social networks in agent-based models: A social circle model
Methods for verifying person's identity through person's social circle using person's photograph
Systems for verifying person's identity through person's social circle using person's photograph