@inproceedings{Å imkovic:2019Bl, author = "Å imkovic, Fedor", title = "{Neutrinoless double beta decay: Theory challenges}", doi = "10.22323/1.337.0064", booktitle = "Proceedings of Neutrino Oscillation Workshop {\textemdash} PoS(NOW2018)", year = 2019, volume = "337", pages = "064" }