Distance Probes of Dark Energy
  This document presents the results from the Distances subgroup of the Cosmic
Frontier Community Planning Study (Snowmass 2013). We summarize the current
state of the field as well as future prospects and challenges. In addition to
the established probes using Type IA supernovae and baryon acoustic
oscillations, we also consider prospective methods based on clusters, active
galactic nuclei, gravitational wave sirens and strong lensing time delays.
