https://github.com/zalandoresearch/flair

https://github.com/zalandoresearch/flair/tree/master/resources/docs
https://github.com/zalandoresearch/flair/blob/master/resources/docs/TUTORIAL_5_DOCUMENT_EMBEDDINGS.md
https://github.com/zalandoresearch/flair/blob/master/resources/docs/TUTORIAL_8_MODEL_OPTIMIZATION.md

2019
http://pusheen-machine.com/zalando-research-vypustil-ochien-prostuiu-bibliotieku-dlia-state-of-the-art-nlp/
2018
https://towardsdatascience.com/text-classification-with-state-of-the-art-nlp-library-flair-b541d7add21f
http://alanakbik.github.io/papers/coling2018.pdf