@article{10_21136_MB_2013_143226,
     author = {Chajda, Ivan and L\"anger, Helmut},
     title = {Groupoids assigned to relational systems},
     journal = {Mathematica Bohemica},
     pages = {15--23},
     publisher = {mathdoc},
     volume = {138},
     number = {1},
     year = {2013},
     doi = {10.21136/MB.2013.143226},
     mrnumber = {3076217},
     zbl = {1274.08002},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/MB.2013.143226/}
}