http://www.gitxiv.com/posts/G4pqRmwMGELtdHdSb/variational-recurrent-neural-network

https://en.wikipedia.org/wiki/Autoencoder#Variational_autoencoder_.28VAE.29

https://arxiv.org/abs/1602.08734

https://arxiv.org/abs/1604.08772

https://arxiv.org/abs/1612.00132

https://arxiv.org/abs/1312.6114