Fixes refs

Author: domna

paper/paper.bib

@@ -320,7 +320,8 @@ @article{Passler19
 @article{Pearce2021, 
   doi = {10.21105/joss.03460},
   url = {https://doi.org/10.21105/joss.03460},
-  year = {2021}, publisher = {The Open Journal}},
+  year = {2021},
+  publisher = {The Open Journal},
   volume = {6},
   number = {65},
   pages = {3460},

paper/paper.md

@@ -75,7 +75,7 @@ In summary, we believe and hope that pyElli will further contribute to easier an
 
 Other notable python open source software for solving transfer-matrices are available, but tend to focus on different aspects:
 
-- [PyGTM](https://pygtm.readthedocs.io) [@Passler17,Passler19]: Slower, but more extensive general transfer matrix approach, calculates additional parameters, like the electric field strengths in the multilayer stack.
+- [PyGTM](https://pygtm.readthedocs.io) [@Passler17; Passler19]: Slower, but more extensive general transfer matrix approach, calculates additional parameters, like the electric field strengths in the multilayer stack.
 - [PyLlama](https://pyllama.readthedocs.io): Provides transfer and scattering matrix algorithms (RCWA), better suited to simulate liquid crystals. Non vectorized.
 - [RayFlare](https://rayflare.readthedocs.io) [@Pearce2021]: Complete toolkit to simulate solar cells. Provides the same 2x2 [@byrnes2020multilayer] algorithm and a scattering matrix approach.
 - Additional mentions: