@article{TAC_2016_31_a3,
     author = {Matej Dostal},
     title = {A two-dimensional {Birkhoff's} theorem},
     journal = {Theory and applications of categories},
     pages = {73--100},
     publisher = {mathdoc},
     volume = {31},
     year = {2016},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2016_31_a3/}
}