@article{TAC_2021_36_a3,
     author = {Ross Street},
     title = {Span composition using fake pullbacks},
     journal = {Theory and applications of categories},
     pages = {102--117},
     year = {2021},
     volume = {36},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2021_36_a3/}
}