@article{TAC_2018_33_a15,
     author = {Seyed Naser Hosseini and Walter Tholen and Leila Yeganeh},
     title = {Lax pullback complements and pullbacks of spans},
     journal = {Theory and applications of categories},
     pages = {445--475},
     publisher = {mathdoc},
     volume = {33},
     year = {2018},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2018_33_a15/}
}