Resolve "update refs for aperiodshr"

Closes #1335 (closed)

topics/bib/aperiodSchr.bib

@@ -19,6 +19,26 @@
       primaryClass={math.SP}
 }
 
+@misc{periodSchr,
+      title={Finite sections of periodic Schr\"odinger operators}, 
+      author={Fabian Gabel and Dennis Gallaun and Julian Großmann and Marko Lindner and Riko Ukena},
+      note={To appear in Operator Theory: Advances and Applications.},
+      year={2021},
+      eprint={2110.09339},
+      archivePrefix={arXiv},
+      primaryClass={math.SP}
+}
+
+@misc{subwords,
+      title={Spectral approximation of generalized Schr\"odinger operators via approximation of subwords}, 
+      author={Fabian Gabel and Dennis Gallaun and Julian Großmann and Marko Lindner and Riko Ukena},
+      year={2022},
+      eprint={arXiv:2209.11613},
+      archivePrefix={arXiv},
+      primaryClass={math.SP}
+}
+
+
 @book{lindner2006infinite,
   title={Infinite Matrices and their Finite Sections: An Introduction to the Limit Operator Method},
   author={Lindner, M.},