Liat Peterfreund, Freydenberger, Dominik D, Kimelfeld, Benny , and Kröll, Markus . 2019. “Complexity Bounds For Relational Algebra Over Document Spanners”. In Proceedings Of The 38Th Acm Sigmod-Sigact-Sigai Symposium On Principles Of Database Systems, Pods 2019, Amsterdam, The Netherlands, June 30 - July 5, 2019, Pp. 320–334. ACM. doi:10.1145/3294052.3319699.