@inproceedings{tokenandtypeconstraintsforcrosslingual,
  title = {Token and Type Constraints for Cross-Lingual Part-of-Speech Tagging},
  author = {Oscar T{\"a}ckstr{\"o}m and Dipanjan Das and Slav Petrov and Ryan Mcdonald and Joakim Nivre},
  year = {2013},
  booktitle = {TACL 2013 1},
  url = {https://aclanthology.org/Q13-1001},
}