E print: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3207372
E print https://arxiv.org/abs/1706.04163
E print: http://arxiv.org/abs/1609.04620
E print http://arxiv.org/abs/1609.02395
E print: arXiv:1604.07556
E-print: http://arxiv.org/abs/1602.03043
E-print: http://arxiv.org/abs/1602.02735
E print: http://arxiv.org/pdf/1601.04478v1
E print: arXiv:1503.06704
E print http://xxx.lanl.gov/abs/1403.5227
E print http://xxx.lanl.gov/abs/1311.4078
E print http://xxx.lanl.gov/abs/1309.3102
E print http://xxx.lanl.gov/abs/1309.5806
E print http://arxiv.org/abs/1304.6819
E print http://arxiv.org/abs/1302.1405
E print: arXiv:1206.2153