@article{DMGAA_2023_43_1_a1,
     author = {Gr\"atzer, George},
     title = {Notes on planar semimodular lattices {IX} \( {\mathcal{C}_1} \)-diagrams},
     journal = {Discussiones Mathematicae. General Algebra and Applications},
     pages = {25--29},
     publisher = {mathdoc},
     volume = {43},
     number = {1},
     year = {2023},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMGAA_2023_43_1_a1/}
}