Perturbative Gravity and Gauge Theory Relations -- A Review
  This review is dedicated to the amazing Kawai-Lewellen-Tye relations, connecting perturbative gravity and gauge theories at tree level. The main focus is on n-point derivations and general properties both from a string theory and pure field theory point of view. In particular the field theory part is based on some very recent developments. 
Thomas Sondergaard
hep-th