@article{TAC_2005_14_a8,
     author = {R. Brown and K.H. Kamps and T. Porter},
     title = {A homotopy double groupoid of a {Hausdorff
space} {II:}  a van {Kampen} theorem},
     journal = {Theory and applications of categories},
     pages = {200--220},
     publisher = {mathdoc},
     volume = {14},
     year = {2005},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2005_14_a8/}
}