@article{JMLR:v21:20-124,
  author  = {Alberto Maria Metelli and Matteo Papini and Nico Montali and Marcello Restelli},
  title   = {Importance Sampling Techniques for Policy Optimization},
  journal = {Journal of Machine Learning Research},
  year    = {2020},
  volume  = {21},
  number  = {141},
  pages   = {1--75},
  url     = {http://jmlr.org/papers/v21/20-124.html}
}